Question

If $f:R\to R,f\left(x\right)=ax+b,a,b\in R,a>0$, then $f$ is.

• A. one-one
• B. onto
• C. one-one onto
• D. none of these

Answer 1

Answer: (C)

one-one onto

$f^{\prime }\left(x\right)=a>0$
Therefore, $f$ is strictly increasing function
Thus, $f$ is one-one
and range of $f$ in $(-\infty ,\infty )$ is $(-\infty ,\infty )$
Therefore, $f$ is onto