Question

What number must you add to complete the square?

x2 + 6x = 15
A. 12
B. 9
C. 6
D. 3

Answer 1

B

Explanation:

x² + 6x = 15

to complete the square

add ( half the coefficient of the x- term )² to both sides

x² + 2(3)x + 9 = 15 + 9

(x + 3)² = 24

thus 9 is added to complete the square