Question

Consider the function $f\left(x\right)=x^2-x-2$. The maximum value of $f\left(x\right)$ in the closed interval $[-4,4]$ is

• A. $18$
• B. $10$
• C. $-2.25$
• D. indeterminate

Answer 1

The correct option is A $18$

$f\left(x\right)=x^2-x-2,xϵ[-4,4]$
$f^{\prime }\left(x\right)=2x-1=0$
$x=\frac{1}{2}ϵ(-4,4)$

$x$	$-4$	$\frac{1}{2}$	$4$
$f\left(x\right)$	$18$	$-\frac{9}{4}$	$10$

Maximum value of $f\left(x\right)=18$