MCQ
The absolute minimum value of $f(x)=2 \sin x$ in $\left[0, \frac{3 \pi}{2}\right]$ is
  • -2
  • B
    2
  • C
    1
  • D
    -1

Answer

Correct option: A.
-2
(a) : Here, $f(x)=2 \sin x$
$\Rightarrow f^{\prime}(x)=2 \cos x$
Putting $f^{\prime}(x)=0 \Rightarrow 2 \cos x=0 \Rightarrow \cos x=0$
$\Rightarrow x=\frac{\pi}{2}, \frac{3 \pi}{2}$
$\therefore \quad \frac{\pi}{2}, \frac{3 \pi}{2}$ are the critical points.
At $x=0, f(x)=2 \sin (0)=0$
At $x=\frac{\pi}{2}, f(x)=2 \times 1=2$
At $x=\frac{3 \pi}{2}, f(x)=2 \sin \left(\pi+\frac{\pi}{2}\right)=-2 \sin \frac{\pi}{2}=-2$
Hence, absolute minimum value of $f(x)$ is -2 .

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

If $f(x) = {x^2} + 2bx + 2{c^2}$ and $g(x) = - {x^2} - 2cx + {b^2}$ such that min $f(x) > $ max $g(x)$, then the relation between $ b$  and $c $ is
$\mathop {\lim }\limits_{n \to \infty } \sum\limits_{r = 1}^n {\frac{1}{n}{e^{\frac{r}{n}}}} $ is
$\int_{}^{} {\frac{{dx}}{{1 + x + {x^2} + {x^3}}} = } $
The period of the function $f\left( x \right)$ = $\frac{x}{3} - \left[ {\frac{x}{3} - 5} \right] + \frac{x}{4} - \left[ {\frac{x}{4} - 5} \right] + \frac{x}{5} - \left[ {\frac{x}{5} - 5} \right]$ is (where $[.]$ is $G.I.F.$ )
The values of $x$ for which the angle between $\vec{\text{a}}=2\text{x}^2\hat{\text{i}}+4\text{x}\hat{\text{j}}+\hat{\text{k}},\vec{\text{b}}=7\hat{\text{i}}-2\hat{\text{j}}+\text{x}\hat{\text{k}}$ is obtuse and the angle between $\vec{\text{b}}$ and the $z-$ axis is acute and less than $\frac{\pi}{6}$ are :
If $D =$ $\left| {\,\begin{array}{*{20}{c}}{\frac{1}{z}}&{\frac{1}{z}}&{ - \frac{{(x + y)}}{{{z^2}}}}\\{ - \frac{{(y + z)}}{{{x^2}}}}&{\frac{1}{x}}&{\frac{1}{x}}\\{ - \frac{{y(y + z)}}{{{x^2}z}}}&{\frac{{x + 2y + z}}{{xz}}}&{ - \frac{{y(x +y)}}{{x{z^2}}}}\end{array}\,} \right|$ then, the incorrect statement is
Two fair dice, each with faces numbered $1,2,3,4,5$ and $6$ , are rolled together and the sum of the numbers on the faces is observed. This process is repeated till the sum is either a prime number or a perfect square. Suppose the sum turns out to be a perfect square before it turns out to be a prime number. If $p$ is the probability that this perfect square is an odd number, then the value of $14 p$ is. . . . . 
Functions $f(x)$ and $g(x)$ are such that $f(x) + \int\limits_0^x {g(t)dt = 2\,\sin \,x\, - \,\frac{\pi }{2}} $ and $f'(x).g (x) = cos^2\,x$ , then number of solution $(s)$ of equation $f(x) + g(x) = 0$ in $(0,3 \pi$) is-
${\cot ^{ - 1}}( - \sqrt 3 ) =$
A binary operation * on Z defined by a * b = 3a + b for all a, b ∈ Z, is: