Complete the square:

Question

y = x² - 6x - 16

(A) y = (x - 4)²

(B) y = (x - 3)² - 16

(C) y = (x - 8) (x + 2)

(D) y = (x - 3)² - 25

(E) none of these

Answer 1

y = x² - 6x - 16

y + 16 = x² - 6x

Add [(1/2)(-6)]² = 9 to both sides to get:

y + 25 = x² - 6x + 9

y = (x - 3)² - 25