Question

If f(x) = 2x − 4 and g(x) = x2 − 4x, find f(-5).

Answer 1

Since we need to find f(-5) and we already have f(x), we don't need g(x) to figure this out, so just ignore it.

Now take the equation for f(x) and replace x with -5 everywhere you see x...as follows:

f(x) = 2x - 4
f(-5) = 2(-5) - 4

Finally, simplify the right side.