### Home > CALC > Chapter 8 > Lesson 8.2.2 > Problem 8-81

8-81.

Expand *f* before differentiating.

Remember that a maximum value is a *y*-value, not an *x*-value.

Notice that this is a CLOSED domain: 0 ≤ *x* ≤ 7.

Since maxima can exist where *f* '(*x*) = 0 or where *f* '(*x*) = DNE, it is important to check the *y*-values at each endpoint. *f*(0) = ________ and *f*(7) = ________

After all, an endpoint might exceed the *y*-values where *f* '(*x*) = 0; in which case, that endpoint will be in the global maximum.