In this case, we'll have to carry out several steps to find the solution.
Step 01:
Data
f(x) = -x^2 - 4x + 13
f(3) = ?
Step 02:
f(x) = - x² - 4x + 13
f(3) = - (3)² - 4(3) + 13
f(3) = - 9 - 12 + 13
f(3) = - 21 + 13
f(3) = - 8
The answer is:
f(3) = - 8