Given the functions f(x) = x + 4 and g(x) = x2 − x find the value of each expression below.

f(x) = x + 4
g(x) = x² - x
a) f(5)
f(5) = 5 + 4 = 9
b) g(-1)
g(-1) = (-1)² -(-1) = 1 + 1 = 2
c) f(x) = 10
10 = x + 4
x = 6
d) g(x) = 6
6 = x² - x
0 = x² - x - 6
0 = (x - 3)(x + 2)
x = 3, -2