Me with this question, it's really frustrating me.

Consider the attached figure. The coordinates of the points are

Since f(x) is even, we have

So, the updated coordinates are

This implies that the rectangle has area

And we want to maximize this function. To so do, let's compute its derivative:

This equals 0 if

Given the behaviour of the area function (cubic polynomial with negative leading coefficient), the first point is a minimum, and the second point is a maximum. So, for x=2, we have

Which yields an area of

pay attention in your classes and concentrate the best thing you can do to raise your test scores is to pay attention when you're supposed to be learning the material: in class!

take good notes.

do your homework.

use mnemonics and other tricks.

do practice tests.

note: the best i know.