CUET UG Mathematics Booster Test 2 - Advanced Differentiation
📌 Answers are locked once submitted — results and explanations appear at the end.
QUESTION 1 OF 20
If integration restores functions, we must know their derivatives. What is the derivative of the composite function
\(y=sin(x^{2})\)?
QUESTION 2 OF 20
Assertion (A): The chain rule can be extended to three functions as
\(\frac{dy}{dx}=\frac{dy}{du}⋅\frac{du}{dv}⋅\frac{dv}{dx}\).
Reason (R): This assumes all internal derivatives inherently exist at their evaluated points.
QUESTION 3 OF 20
Which of the following derivatives correctly apply polynomial composition?
I. \(y=(x^{2}+1)^{5}\)requires the chain rule multiple times.
II. \(\frac{d}{dx}(x^{2}+1)^{5}=5(x^{2}+1)^{4}⋅2x\).
III. The derivative of \(y=(x^{3}+2x)^{4}\)is strictly \(4(x^{3}+2x)^{3}⋅(3x^{2}+2)\).
QUESTION 4 OF 20
Match the composite trigonometric functions to their derivatives:
| List I | List II |
|---|---|
| 1. \(sin(x^{2})\) | a. \(2xcos(x^{2})\) |
| 2. \(cos(3x)\) | b. \(-3sin(3x)\) |
| 3. \(tan(x^{3})\) | c. \(3x^{2}{sec}^{2}(x^{3})\) |
QUESTION 5 OF 20
Arrange the process to differentiate
\(y=log(2x^{2}+1)\):
1. Convert base using change of base: \(loga=lna/ln10\)
2. Identify the constant scalar \(1/ln10\)
3. Evaluate the derivative using the chain rule as \(1/(2x^{2}+1)⋅4x\)
4. Differentiate to get final result
QUESTION 6 OF 20
A directional vector constraint uses
\(\vec{r}(t)=(t^{2})\hat{i}+(sint)\hat{j}\).
By the extended chain rule, its outer derivative operation results directly in:
QUESTION 7 OF 20
If cumulative probability establishes an implicit form
\(x^{2}+y^{2}=1\),
why must we use implicit differentiation?
QUESTION 8 OF 20
The bounded area relation is
\(x^{2}+xy+y^{2}=9\).
Differentiating implicitly with respect to \(x\) provides the slope relation as:
QUESTION 9 OF 20
Differentiating the graphical relation
\(x^{2}+y^{2}=4\)
directly yields \(dy/dx\) equal to:
QUESTION 10 OF 20
In the implicit relation
\(xy=6\),
treat \(y\) as a function of \(x\). If \(x=2\), what is the real numeric value of \(dy/dx\)?
QUESTION 11 OF 20
Given a simplistic moving relation
\(2x+3y=12\),
the derivative evaluates to:
QUESTION 12 OF 20
Which implicitly differentiated statement is mathematically INCORRECT regarding
\(sin(xy)=x\)?
QUESTION 13 OF 20
Using \(siny=x\), the derivative of \({sin}^{-1}x\) equates to
\(1/cosy\).
What identity is utilized to substitute \(\cos\,y\) in terms of \(x\)?
QUESTION 14 OF 20
\(y=a^{x},a>0,a\neq 1\).
The domain of the exponential function is the set of all real numbers \(\left(-\infty ,\infty \right)\), and its range is strictly the set of all positive real numbers \(\left(0,\ \infty \right)\). The point \(\left(0,\ 1\right)\)is always on the graph of the exponential function. If we set the base \(a=e\), we obtain the natural exponential function
\(y=e^{x}\).
The logarithmic function is mathematically its inverse, defined such that if
\(y=e^{x}\)then \(x=lny\).
QUESTION 15 OF 20
\(y=a^{x},a>0,a\neq 1\).
The domain of the exponential function is the set of all real numbers \(\left(-\infty ,\infty \right)\), and its range is strictly the set of all positive real numbers \(\left(0,\ \infty \right)\). The point \(\left(0,\ 1\right)\)is always on the graph of the exponential function. If we set the base \(a=e\), we obtain the natural exponential function
\(y=e^{x}\).
The logarithmic function is mathematically its inverse, defined such that if
\(y=e^{x}\)then \(x=lny\).
\(y=e^{x}\)translates to \(x=lny\),
what specific base forms the natural exponential function?
QUESTION 16 OF 20
Differentiating \({tan}^{-1}x\) relies on trigonometric simplification. It simplifies to
\(1/(1+x^{2})\).
What is \(d/dx({tan}^{-1}x)\)?
QUESTION 17 OF 20
For logarithmic differentiation, evaluating expressions like \(ln(x)\)requires taking logarithms. The interval for \(x\) must strictly be:
QUESTION 18 OF 20
The logarithmic function \(\ln\,x\) is restricted from taking non-positive numbers. Hence, its valid domain is:
QUESTION 19 OF 20
Applying logarithmic differentiation to
\(y=x^{x},x>0\),
yields:
QUESTION 20 OF 20
In functional differentiation, the derivative of
\(y=ln(x^{2}+1)\)
for all real \(x\) is:
Test Complete!
Answer Review
1 If integration restores functions, we must know their derivatives. What is the derivative of the composite function
\(y=sin(x^{2})\)?
\(sin(x^{2})\)is a composite function. Apply the chain rule. Differentiate outer and inner functions separately.
The function \(y=sin(x^{2})\)contains an outer trigonometric function and an inner polynomial function. Using the chain rule: \(\frac{d}{dx}[sin(x^{2})]=cos(x^{2})⋅2x\) Option C is correct because both the derivative of \(\sin\,u\) and the derivative of \(u=x^{2}\)are included. Option A ignores the inner derivative, Option B uses the wrong trigonometric function, and Option D incorrectly simplifies the expression.
- Option A → \(cos(x^{2})\)ignores differentiation of the inner function \(x^{2}\). Chain rule is incomplete.
- Option B → Uses \(sin(x^{2})\)instead of \(cos(x^{2})\). Derivative of sine is cosine.
- Option D → \(sin(2x)\)is unrelated to differentiation of \(sin(x^{2})\). It incorrectly changes the function itself.
Used
- Elimination
Application:
- Identify the outer function \(\sin\,u\) and inner function \(u=x^{2}\). Eliminate options missing either cosine or factor \(2x\).
Final Logic:
- Chain rule requires multiplying derivative of outer and inner functions.
"SIN becomes COS, multiply inside loss."
2 Assertion (A): The chain rule can be extended to three functions as
\(\frac{dy}{dx}=\frac{dy}{du}⋅\frac{du}{dv}⋅\frac{dv}{dx}\).
Reason (R): This assumes all internal derivatives inherently exist at their evaluated points.
Extended chain rule connects nested derivatives. Internal derivatives must exist. Reason correctly explains assertion.
The extended chain rule applies when variables depend successively on one another. If \(y\) depends on \(u\), \(u\) on \(v\), and \(v\) on \(x\), then derivatives multiply successively: \(\frac{dy}{dx}=\frac{dy}{du}⋅\frac{du}{dv}⋅\frac{dv}{dx}\) The rule works only when all intermediate derivatives exist. Therefore, both Assertion and Reason are true, and the Reason correctly explains the Assertion.
- Option A → Incorrect because both the formula and the condition regarding existence of derivatives are mathematically valid.
- Option B → Assertion is true, not false. The chain rule extension is standard differentiation theory.
- Option D → Reason is also true because differentiability assumptions are necessary for the chain rule.
Used
- Contextual/Tonal Matching
Application:
- Check whether the reason logically supports the assertion rather than merely being independently true.
Final Logic:
- The reason directly states the condition required for the chain rule to hold.
"Derivative chain works only if every link exists."
3 Which of the following derivatives correctly apply polynomial composition?
I. \(y=(x^{2}+1)^{5}\)requires the chain rule multiple times.
II. \(\frac{d}{dx}(x^{2}+1)^{5}=5(x^{2}+1)^{4}⋅2x\).
III. The derivative of \(y=(x^{3}+2x)^{4}\)is strictly \(4(x^{3}+2x)^{3}⋅(3x^{2}+2)\).
Composite polynomial functions use chain rule. Inner derivatives are multiplied. All three statements are valid.
Both given functions are compositions of inner polynomial expressions and outer power functions. Using the chain rule: \(\frac{d}{dx}(x^{2}+1)^{5}=5(x^{2}+1)^{4}⋅2x\) and \(\frac{d}{dx}(x^{3}+2x)^{4}=4(x^{3}+2x)^{3}(3x^{2}+2)\) Statement I is true because polynomial composition requires chain rule application. Hence all statements are correct.
- Option A → Ignores correct derivative formulas in Statements II and III.
- Option B → Statement I is also true because composed powers require chain rule.
- Option C → Statement II is correctly differentiated and cannot be excluded.
Used
- Option Grouping
Application:
- Verify each statement independently using derivative formulas and identify the option containing all valid statements.
Final Logic:
- All three statements satisfy standard chain rule differentiation.
"Power outside → derivative inside."
4 Match the composite trigonometric functions to their derivatives:
| List I | List II |
|---|---|
| 1. \(sin(x^{2})\) | a. \(2xcos(x^{2})\) |
| 2. \(cos(3x)\) | b. \(-3sin(3x)\) |
| 3. \(tan(x^{3})\) | c. \(3x^{2}{sec}^{2}(x^{3})\) |
Differentiate each composite function separately. Use standard trigonometric derivatives. Apply chain rule for inner functions.
Using chain rule: \(\frac{d}{dx}[sin(x^{2})]=2xcos(x^{2})\frac{d}{dx}[cos(3x)]=-3sin(3x)\frac{d}{dx}[tan(x^{3})]=3x^{2}{sec}^{2}(x^{3})\) Thus matching becomes \(1-a,2-b,3-c\). Option A correctly pairs each function with its derivative.
- Option B → Interchanges derivatives of sine and cosine incorrectly.
- Option C → Assigns sec² derivative to cosine function incorrectly.
- Option D → Completely mismatches trigonometric derivative patterns and inner derivatives.
Used
- Elimination
Application:
- Differentiate each function quickly and eliminate mismatched derivative structures.
Final Logic:
- Each derivative uniquely matches only one function.
"SIN→COS, COS→−SIN, TAN→SEC²."
5 Arrange the process to differentiate
\(y=log(2x^{2}+1)\):
1. Convert base using change of base: \(loga=lna/ln10\)
2. Identify the constant scalar \(1/ln10\)
3. Evaluate the derivative using the chain rule as \(1/(2x^{2}+1)⋅4x\)
4. Differentiate to get final result
Convert logarithm to natural log first. Separate constant factor. Apply chain rule and simplify.
The correct differentiation order is: 1. Convert common logarithm using \(loga=\frac{\ln\,a}{\ln\,10}\). 2. Take constant \(\frac{1}{\ln\,10}\)outside differentiation. 3. Differentiate \(ln(2x^{2}+1)\)using chain rule. 4. Simplify the final expression. Therefore, the correct sequence is \(1,2,3,4\). The provided answer B is incorrect.
- Option B → Final differentiation cannot occur before applying chain rule. Sequence is logically inconsistent.
- Option C → Constant scalar cannot be identified before logarithmic conversion.
- Option D → Reverse ordering ignores the actual differentiation process.
Used
- Contextual/Tonal Matching
Application:
- Follow the natural procedural order used in logarithmic differentiation.
Final Logic:
- Conversion and simplification must precede differentiation.
"Convert → Constant → Chain → Simplify."
6 A directional vector constraint uses
\(\vec{r}(t)=(t^{2})\hat{i}+(sint)\hat{j}\).
By the extended chain rule, its outer derivative operation results directly in:
Differentiate vector components separately. Derivative of \(t^{2}\)is \(2t\). Derivative of \(\sin\,t\) is \(\cos\,t\).
Vector differentiation is performed component-wise: \(\frac{d}{dt}\left[(t^{2})\hat{i}+(sint)\hat{j}\right]=2t\hat{i}+cost\hat{j}\) Option C correctly differentiates both components. Options A and B leave one component undifferentiated, while Option D interchanges derivatives incorrectly.
- Option A → No differentiation has been performed. Original vector remains unchanged.
- Option B → Only first component is differentiated; second component remains incorrect.
- Option D → Swaps derivatives between vector components incorrectly.
Used
- Elimination
Application:
- Differentiate each vector component independently and reject partially differentiated results.
Final Logic:
- Both components must be differentiated simultaneously.
"Vector derivative = component derivative."
7 If cumulative probability establishes an implicit form
\(x^{2}+y^{2}=1\),
why must we use implicit differentiation?
Equation contains both x and y together. y is not directly explicit. Implicit differentiation handles such relations.
Implicit differentiation is used when variables are mixed in one equation and isolating \(y\) is difficult or inconvenient. In \(x^{2}+y^{2}=1\), differentiating directly gives the slope relation efficiently. Option D correctly explains the need for implicit differentiation. Other options do not describe the actual mathematical reason.
- Option A → The equation is nonlinear because squares of variables are present.
- Option B → Derivative is not zero; differentiation produces a variable slope.
- Option C → Parametric equations involve another parameter, which is absent here.
Used
- Elimination
Application:
- Remove options unrelated to implicit relations and identify the conceptual purpose of implicit differentiation.
Final Logic:
- Implicit differentiation is needed when explicit isolation is inconvenient.
"Mixed x and y → implicit apply."
8 The bounded area relation is
\(x^{2}+xy+y^{2}=9\).
Differentiating implicitly with respect to \(x\) provides the slope relation as:
Differentiate every term separately. Use product rule for \(xy\). Rearrange to isolate \(dy/dx\).
Differentiating implicitly: \(\frac{d}{dx}(x^{2}+xy+y^{2})=0\) gives \(2x+x\frac{dy}{dx}+y+2y\frac{dy}{dx}=0\) Collecting derivative terms: \(\left(x+2y)\frac{dy}{dx}=-(2x+y\right)\) Thus, \(\frac{dy}{dx}=\frac{-2x-y}{x+2y}\) Hence Option A is correct.
- Option B → Sign error occurs while rearranging derivative terms.
- Option C → Denominator incorrectly changes to \(x-2y\).
- Option D → Numerator sign is incorrect after transposition.
Used
- Substitution
Application:
- Apply implicit differentiation systematically and isolate derivative terms carefully.
Final Logic:
- Correct algebraic rearrangement gives Option A.
"Differentiate → collect dy/dx → isolate."
9 Differentiating the graphical relation
\(x^{2}+y^{2}=4\)
directly yields \(dy/dx\) equal to:
Differentiate both sides implicitly. Treat y as function of x. Rearrange for dy/dx.
Differentiating implicitly: \(2x+2y\frac{dy}{dx}=0\) Solving: \(2y\frac{dy}{dx}=-2x\frac{dy}{dx}=-\frac{x}{y}\) Thus Option B is correct. The negative sign appears due to transposition after differentiation.
- Option A → Missing negative sign from rearrangement.
- Option C → Variables are inverted incorrectly.
- Option D → Both sign and variable positions are incorrect.
Used
- Elimination
Application:
- Check sign and variable placement after implicit differentiation.
Final Logic:
- Derivative simplifies exactly to \(-x/y\).
"Circle slope = minus x by y."
10 In the implicit relation
\(xy=6\),
treat \(y\) as a function of \(x\). If \(x=2\), what is the real numeric value of \(dy/dx\)?
Differentiate using product rule. Substitute \(x=2\) and \(y=3\). Simplify derivative value.
From \(xy=6\): \(x\frac{dy}{dx}+y=0\) So, \(\frac{dy}{dx}=-\frac{y}{x}\) When \(x=2\), using \(xy=6\), we get \(y=3\). Hence: \(\frac{dy}{dx}=-\frac{3}{2}\) Thus the correct value is \(-3/2\). Option labels repeat the same value, but Option A is selected first correctly.
- Option B → Incorrect numerical substitution.
- Option C → Sign error; derivative should be negative.
- Option D → Though numerically identical to A, duplicate options violate uniqueness. First correct occurrence is chosen.
Used
- Substitution
Application:
- Differentiate first, then substitute known coordinate values into the derivative expression.
Final Logic:
- Using \(y=6/x\) at \(x=2\) gives slope \(-3/2\).
"For \(xy=c\), slope = \(-y/x\)."
11 Given a simplistic moving relation
\(2x+3y=12\),
the derivative evaluates to:
Differentiate both sides implicitly. Derivative of constant is zero. Solve for \(dy/dx\).
Differentiating implicitly: \(\frac{d}{dx}(2x+3y)=0\) gives: \(2+3\frac{dy}{dx}=0\) So, \(\frac{dy}{dx}=-\frac{2}{3}\) Option A is correct. Since the equation is linear, the slope remains constant throughout the graph.
- Option B → Incorrect sign. Rearranging produces a negative slope.
- Option C → Reciprocal taken incorrectly; denominator and numerator are interchanged.
- Option D → Derivative is not zero because the equation changes with x.
Used
- Substitution
Application:
- Differentiate term-wise and isolate \(dy/dx\) using simple algebra.
Final Logic:
- Linear equations give constant slopes after differentiation.
"For \(ax+by=c\), slope = \(-a/b\)."
12 Which implicitly differentiated statement is mathematically INCORRECT regarding
\(sin(xy)=x\)?
Differentiate using chain rule. Product rule applies to \(xy\). Option B ignores derivative of \(xy\).
Differentiating implicitly: \(\frac{d}{dx}[sin(xy)]=cos(xy)⋅\frac{d}{dx}(xy)\) Using the product rule: \(\frac{d}{dx}(xy)=x\frac{dy}{dx}+y\) Hence, \(cos(xy)(x\frac{dy}{dx}+y)=1\) Option B is incorrect because it ignores differentiation of the product \(xy\). Therefore, only \(dy/dx\) is insufficient.
- Option A → Correct because chain rule is necessary for differentiating \(sin(xy)\).
- Option C → Correct since \(xy\) requires product rule differentiation.
- Option D → Correct complete differentiation result after applying chain and product rules.
Used
- Elimination
Application:
- Check whether both chain rule and product rule are fully applied.
Final Logic:
- Any expression missing \(x(dy/dx)+y\) is incomplete.
"SIN outside, PRODUCT inside."
13 Using \(siny=x\), the derivative of \({sin}^{-1}x\) equates to
\(1/cosy\).
What identity is utilized to substitute \(\cos\,y\) in terms of \(x\)?
Use trigonometric identity. \({sin}^{2}y+{cos}^{2}y=1\). Replace \(\sin\,y\) by \(x\).
Given \(siny=x\), using the identity: \({sin}^{2}y+{cos}^{2}y=1\) \(\theta\) \({sin}^{2}\theta \approx 0.329, {cos}^{2}\theta \approx 0.671\) \({sin}^{2}\theta +{cos}^{2}\theta \approx 1\) θ = 35°|cos θ| = 0.819|sin θ| = 0.574cos² θsin² θ0.671 + 0.329 = 1 we obtain: \(x^{2}+{cos}^{2}y=1\) Thus, \(cosy=\sqrt{1-x^{2}}\) Substituting into the derivative formula gives: \(\frac{d}{dx}({sin}^{-1}x)=\frac{1}{\sqrt{1-x^{2}}}\) Hence Option A is correct.
- Option B → Missing square root; identity is incomplete.
- Option C → Incorrect sign arrangement from trigonometric identity.
- Option D → No standard trigonometric identity produces this relation.
Used
- Substitution
Application:
- Replace \(\sin\,y\) by \(x\) in the Pythagorean identity.
Final Logic:
- Inverse trigonometric derivatives depend on standard identities.
"SIN² + COS² = 1."
14
\(y=a^{x},a>0,a\neq 1\).
The domain of the exponential function is the set of all real numbers \(\left(-\infty ,\infty \right)\), and its range is strictly the set of all positive real numbers \(\left(0,\ \infty \right)\). The point \(\left(0,\ 1\right)\)is always on the graph of the exponential function. If we set the base \(a=e\), we obtain the natural exponential function
\(y=e^{x}\).
The logarithmic function is mathematically its inverse, defined such that if
\(y=e^{x}\)then \(x=lny\).
Exponential functions accept every real x-value. Domain is unrestricted. Passage explicitly states the interval.
The passage clearly states that the domain of the exponential function \(y=a^{x}\)is all real numbers: \(\left(-\infty ,\infty \right)\) This means every real value of \(x\) is allowed. Option B directly matches the statement in the passage. The range, not domain, is restricted to positive real numbers.
- Option A → Describes the range, not the domain, of exponential functions.
- Option C → Incorrect restriction; exponential functions are defined beyond this interval.
- Option D → Domain includes all real numbers, not merely integers.
Used
- Contextual/Tonal Matching
Application:
- Locate the exact phrase defining the domain within the passage.
Final Logic:
- The passage explicitly mentions "all real numbers."
"Exponential accepts every x."
15
\(y=a^{x},a>0,a\neq 1\).
The domain of the exponential function is the set of all real numbers \(\left(-\infty ,\infty \right)\), and its range is strictly the set of all positive real numbers \(\left(0,\ \infty \right)\). The point \(\left(0,\ 1\right)\)is always on the graph of the exponential function. If we set the base \(a=e\), we obtain the natural exponential function
\(y=e^{x}\).
The logarithmic function is mathematically its inverse, defined such that if
\(y=e^{x}\)then \(x=lny\).
\(y=e^{x}\)translates to \(x=lny\),
what specific base forms the natural exponential function?
Natural exponential function uses Euler's number. Base is denoted by \(e\). Passage directly states this.
The passage explicitly defines the natural exponential function as: \(y=e^{x}\) Hence its base is \(e\), known as Euler's number. Option C correctly identifies the special base associated with natural logarithms and exponential functions.
- Option A → Base 10 corresponds to common logarithms, not natural exponential functions.
- Option B → \(\pi\) is unrelated to exponential base definitions.
- Option D → Base 2 defines binary exponential functions, not natural exponentials.
Used
- Contextual/Tonal Matching
Application:
- Read the exact definition of the natural exponential function from the passage.
Final Logic:
- Natural exponential means exponential with base \(e\).
"Natural log pairs with base e."
16 Differentiating \({tan}^{-1}x\) relies on trigonometric simplification. It simplifies to
\(1/(1+x^{2})\).
What is \(d/dx({tan}^{-1}x)\)?
Use inverse trigonometric differentiation formula. Derivative remains always positive. Simplifies using secant identity.
For \(y={tan}^{-1}x\), let \(tany=x\). Differentiating: \({sec}^{2}y\frac{dy}{dx}=1\) Using \({sec}^{2}y=1+{tan}^{2}y\) and \(tany=x\): \(\frac{d}{dx}({tan}^{-1}x)=\frac{1}{1+x^{2}}\) Thus Option D is correct. The derivative is always positive.
- Option A → Formula belongs to derivative of \({sin}^{-1}x\).
- Option B → Incorrect sign and wrong inverse trigonometric derivative.
- Option C → Negative sign is incorrect for \({tan}^{-1}x\).
Used
- Elimination
Application:
- Identify standard inverse trigonometric derivative formulas and remove mismatched expressions.
Final Logic:
- Only Option D matches the standard derivative identity.
"TAN inverse → one plus x-square."
17 For logarithmic differentiation, evaluating expressions like \(ln(x)\)requires taking logarithms. The interval for \(x\) must strictly be:
Natural logarithm is defined only for positives. Zero and negatives are excluded. Domain restriction is essential.
The logarithmic function \(\ln\,x\) is defined only for positive real numbers. Therefore, logarithmic differentiation requires: \(x>0\) Option A correctly gives the domain condition. Negative numbers and zero are not included in the logarithm's domain.
- Option B → Logarithms are undefined for negative real values.
- Option C → Zero and negative numbers cannot be included.
- Option D → Still incorrectly allows negative numbers.
Used
- Elimination
Application:
- Recall the standard domain of logarithmic functions.
Final Logic:
- Natural logarithm exists only for positive inputs.
"LOG likes positives only."
18 The logarithmic function \(\ln\,x\) is restricted from taking non-positive numbers. Hence, its valid domain is:
Logarithms require positive inputs. Non-positive numbers are excluded. Domain is strictly positive.
The natural logarithm function exists only when its argument is positive: \(x>0\) Hence Option B correctly states the domain. Values equal to zero or less than zero are invalid inputs for logarithmic functions.
- Option A → Includes zero and negative values, which are invalid.
- Option C → Logarithm is not defined for all real numbers.
- Option D → Allows negative values incorrectly.
Used
- Elimination
Application:
- Remove every option that includes zero or negative numbers.
Final Logic:
- Positive real numbers form the logarithmic domain.
"No positive, no logarithm."
19 Applying logarithmic differentiation to
\(y=x^{x},x>0\),
yields:
Take logarithm on both sides. Differentiate implicitly. Multiply final result by \(x^{x}\).
Given: \(y=x^{x}\) Taking logarithm: \(lny=xlnx\) Differentiating: \(\frac{1}{y}\frac{dy}{dx}=1+lnx\) Multiplying by \(y=x^{x}\): \(\frac{d}{dx}(x^{x})=x^{x}(1+lnx)\) Thus Option C is correct.
- Option A → Represents the original function, not its derivative.
- Option B → Incorrect multiplication by \(x\); logarithmic term is missing.
- Option D → Completely unrelated differentiation result.
Used
- Substitution
Application:
- Use logarithmic differentiation and substitute back the original function.
Final Logic:
- Differentiation of \(xlnx\) gives \(1+lnx\).
"\(x^{x}\) → add \(1+lnx\)."
20 In functional differentiation, the derivative of
\(y=ln(x^{2}+1)\)
for all real \(x\) is:
Use derivative of logarithm. Apply chain rule to inner function. Differentiate \(x^{2}+1\) separately.
For logarithmic differentiation: \(\frac{d}{dx}[ln(x^{2}+1)]=\frac{1}{x^{2}+1}⋅2x\) Thus, \(\frac{dy}{dx}=\frac{2x}{x^{2}+1}\) Option B is correct. Option D is numerically identical but duplicated. First correct occurrence is selected.
- Option A → Inner derivative \(2x\) is missing.
- Option C → Incorrect differentiation of logarithmic composition.
- Option D → Duplicate of correct answer; first correct occurrence is preferred.
Used
- Elimination
Application:
- Apply chain rule and eliminate incomplete logarithmic derivatives.
Final Logic:
- Derivative of \(\ln\,u\) equals \(u^{'}/u\).
"LOG derivative = inside derivative over inside."
