MCQ
The function $x + {1 \over x},(x \ne 0)$ is a non-increasing function in the interval
- ✓$[-1, 1]$
- B$[0, 1]$
- C$[-1, 0]$
- D$[-1,2]$
Differentiating with respect to $ x,$ we get
$\frac{{dy}}{{dx}} = f'(x) = 1 - \frac{1}{{{x^2}}} \le 0$
$\, \Rightarrow 1 \le \frac{1}{{{x^2}}}$ or ${x^2} \le 1$
Hence $x \in [ - 1,\,1]$.
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If the derivative $f^{\prime}$ of $f$ satisfies the equation $f ^{\prime}( x )=\frac{ f ( x )}{ b ^2+ x ^2}$ for all $x \in R$, then which of the following statements is/are TRUE?
$(A)$ If $b>0$, then $f$ is an increasing function
$(B)$ If $b<0$, then $f$ is a decreasing function
$(C)$ $(x)(-x)=1$ for all $x \in R$
$(D)$ $(x)-f(-x)=0$ for all $x \in R$
$A=\left\{(x, y):|\cos x-\sin x| \leq y \leq \sin x, 0 \leq x \leq \frac{\pi}{2}\right\}$