Match List-I with List-II
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List-I |
List-II |
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(A) Maximum value of $f(x) = \sin^2 x -\cos^2 x ∀x ∈ (π,2π)$ is |
(I) 0 |
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(B) Minimum value of $f(x) = \sin x.\cos x$ |
(II) 1 |
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(C) Point of Minima of $f(x) = x^x (x > 0)$ |
(III) $-\frac{1}{2}$ |
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(D) Maximum value of $f(x) = -x^{2026}$ |
(IV) $\frac{1}{e}$ |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (4) → (A)-(II), (B)-(III), (C)-(IV), (D)-(I)
|
List-I |
List-II |
|
(A) Maximum value of $f(x) = \sin^2 x- \cos^2 x ∀x ∈ (π,2π)$ is |
(II) 1 |
|
(B) Minimum value of $f(x) = \sin x.\cos x$ |
(III) $-\frac{1}{2}$ |
|
(C) Point of Minima of $f(x) = x^x (x > 0)$ |
(IV) $\frac{1}{e}$ |
|
(D) Maximum value of $f(x) = -x^{2026}$ |
(I) 0 |
$\text{(A) Maximum value of }f(x)=\sin^2 x-\cos^2 x\text{ for }x\in(\pi,2\pi)$
$\sin^2 x-\cos^2 x=-\cos 2x$
$x\in(\pi,2\pi)\Rightarrow 2x\in(2\pi,4\pi)$
$-\cos 2x$ takes its maximum value $1$.
(A) → (II)
$\text{(B) Minimum value of }f(x)=\sin x\cdot\cos x$
$\sin x\cos x=\frac{1}{2}\sin 2x$
Minimum value is $-\frac{1}{2}$.
(B) → (III)
$\text{(C) Point of minima of }f(x)=x^x,\;x>0$
$f(x)=x^x$
$\ln f=x\ln x$
$\frac{f'}{f}=\ln x+1=0$
$x=\frac{1}{e}$ gives minima.
(C) → (IV)
$\text{(D) Maximum value of }f(x)=-x^{2026}$
Since $2026$ is even, $x^{2026}\ge 0$.
$-x^{2026}$ is maximized at $x=0$ giving value $0$.
(D) → (I)