Use the definition of continuity to determine whether f is continuous at a. f(x) = 5x4 - 9x3 + x - 7a = 7

We have . By the definition of continuity, we require that

So for any , we want to find sufficient for which

We have

Suppose we let . Then

so that

which suggests that it suffices to choose

in order to meet the required condition.

-2x + 7 = 7

subtract 7 from both sides.

-2x = 0

divide both sides by -2.

x = 0