Question
The function $f(x)=k \ x - \sin\ x$ is strictly increasing for

Answer

Given $, f(x)=k\ x-\sin x$
$\Rightarrow f^{\prime}(x)=k-\cos x>0 $
$\quad(\because f(x) \text { is strictly increasing } \therefore f(x)>0)$
$\Rightarrow k>\cos x$
$\therefore k>1 \quad (\because \cos x \in[-1,1])$

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

$\int\limits^{\frac{\pi}{3}}_{\frac{\pi}{6}}\frac{1}{1+\sqrt{\cot\text{x}}}\text{ dx}$ is:
  1. $\frac{\pi}{3}$
  2. $\frac{\pi}{6}$
  3. $\frac{\pi}{12}$
  4. $\frac{\pi}{2}$
If the vectors $4\hat{\text{i}}+11\hat{\text{j}}+\text{m}\hat{\text{k}},7\hat{\text{i}}+2\hat{\text{j}}+6\hat{\text{k}}$ and $\hat{\text{i}}+5\hat{\text{j}}+4\hat{\text{k}}$ are coplanar, then $m =$
If $A=\left[a_{i j}\right]=\left[\begin{array}{cc}2 & -1 \\ -3 & 4 \\ 1 & 2\end{array}\right]$ and $B=\left[b_{i j}\right]=\left[\begin{array}{ccc}2 & 3 & -5 \\ 1 & 4 & 9 \\ 0 & 7 & -2\end{array}\right]$, then value of $a_{11} b_{11}+a_{22} b_{22}$ is
If the lines $\frac{x-1}{-3}=\frac{y-2}{2 k}=\frac{z-3}{2}$ and $\frac{x-1}{3 k}=\frac{y-1}{1}=\frac{z-6}{-5}$ are perpendicular to each other then $k = ?$
In a $\triangle\text{ABC},$ if C is a right angle, then $\tan^{-1}\Big(\frac{\text{a}}{\text{b}+\text{c}}\Big)+\tan^{-1}\Big(\frac{\text{b}}{\text{c}+\text{b}}\Big)=$
  1. $\frac{\pi}{3}$
  2. $\frac{\pi}{4}$
  3. $\frac{5\pi}{2}$
  4. $\frac{\pi}{6}$
The sum of the order and degree of the differential equation $1+\left(\frac{d y}{d x}\right)^4=7\left(\frac{d^2 y}{d x^2}\right)^3$ is
If $\text{D}_\text{k}=\begin{vmatrix}1&\text{n}&\text{n}\\2\text{k}&\text{n}^2+\text{n}+2&\text{n}^2+\text{n}\\2\text{k}-1&\text{n}^2&\text{n}^2+\text{n}+2\end{vmatrix} $ and $\sum\limits_{\text{k}=1}^\text{n}\text{D}_\text{k}=48,$ then n equals:
  1. 4
  2. 6
  3. 8
  4. None of these.
If $\text{A}=\begin{bmatrix}\cos\theta -\sin\theta \sin\theta \cos\theta\end{bmatrix},$ then $A^T + A = I_2,$ if:
A random variable X has the following probability distribution:
X: 1 2 3 4 5 6 7 8
P(X): 0.15 0.23 0.12 0.10 0.20 0.08 0.07 0.05
Find the events E = {X : X is a prime number}, F{X : X < 4}, the probability $\text{P}(\text{E}\cup\text{F})$ is:
  1. 0.50
  2. 0.77
  3. 0.35
  4. 0.87
In a sphere the rate of change of volume is:
  1.  $\pi$ times the rate of change of radius.
  2.  Surface area times the rate of change of diameter.
  3.  Surface area times the rate of change of radius.
  4.  None of these.