Consider the functions f (x) = x2 - 13 and g (x) = x + 5. What is the value of f[g (-4) ]?

-12

3

-13

8

The value of that composite function is - 12.

In order to solve for any value within a composite function, we first take the number and function on the innermost part and ignore the outermost part. In this case, we start with just g (-4). This means we stick - 4 in for x in the g equation. The work for this is below.

g (x) = x + 5

g (-4) = - 4 + 5

g (-4) = 1

Now that we have this, we use the answer (in this case 1) and put it into the outermost equation. So we are looking for f (1), which means we stick 1 in for x in the f equation.

f (x) = x^2 - 13

f (1) = 1^2 - 13

f (1) = 1 - 13

f (1) = - 12