f(x) = (x + 2)² - 25
f(x) = (x + 2)(x + 2) - 25
f(x) = x(x + 2) + 2(x + 2) - 25
f(x) = x(x) + x(2) + 2(x) + 2(2) - 25
f(x) = x² + 2x + 2x + 4 - 25
f(x) = x² + 4x + 4 - 25
f(x) = x² + 4x - 21
0 = x² + 4x - 21
x = -(4) ± √((4)² - 4(1)(-21))
2(1)
x = -4 ± √(16 + 84)
2
x = -4 ± √(100)
2
x = -4 ± 10
2
x = -2 ± 5
x = -2 + 5 U x = -2 - 5
x = 3 U x = -7
The solution set is {3, -7}.
