Question

lf $f\left(x\right)=$ kx - sinx is monotonically increasing then

• A. $k>1$
• B. $k>-1$
• C. $k<1$
• D. $k<-1$

Answer 1

The correct option is A $k>1$

$f\left(x\right)=k-cosx$
$f^{\prime }\left(x\right)>0$ for the function to be mononically increasing.

$\therefore cosx<1$ for $\forall xϵR$
So $f^1\left(x\right)>0$ If $k>1$