Question

Find the value of x at which f(x) = $7-(4-x{)}^2$ is maximum.

• A. $-9$
• B. $-3$
• C. $3$
• D. $4$
• E. $7$

Answer 1

The correct option is D $4$

$f\left(x\right)=7-{(4-x)}^2$ , for $f\left(x\right)$ to be maximum $7-{(4-x)}^2$ should be maximum , which implies ${(4-x)}^2$ should be minimum.
The minimum value of ${(4-x)}^2$ is $0$ which occurs at $x=4$.
So, the maximum value of $f\left(x\right)$ is $7$ and occurs at $x=4$.