Question

What number must you add to complete the square x^2+8=-3?

A. 16
B. 8
C. 4
D. 64

Answer 1

$x^2 + 8x = -3$

$x^2 + 8x + (8/2)^2 = -3 + (8/2)^2$

$x^2 + 8x + 16 = -3 + 16$

Answer: A 16

$(x + 4)^2 = 13$