If f(x) = 6x + 6, find f(-4).
Note
Substitute x = -4 into the function: f(-4) = 6 × -4 + 6 = -18. A function gives an output for each input. To evaluate f(x), replace every x in the rule with the given number before simplifying. Be especially careful with negative inputs, because multiplying two negative signs can make a positive result. The correct answer is -18, which matches the calculation or reasoning shown.
