Question

The function $f\left(x\right)=ax+b$ is strictly increasing for all real $x$, if

• A. $a>0$
• B. $a<0$
• C. $a=0$
• D. $a\le 0$

Answer 1

Answer: (A)

$a>0$

Given, $f\left(x\right)=ax+b$
On differentiating w.r.t $x$ we get
$f^{\prime }\left(x\right)=a$
For strictly increasing, $f^{\prime }\left(x\right)>0$
$\Rightarrow$ $a>0$