Question

Complete the square to solve 3x2 + 12x = 9.

O A. x=2+1
O B. %= 3 + 6
OC. X=-2+
O D.%-
D. x=-2 + 13

Answer 1

C) x = -2 ±
`√(7)`

Explanation:

3x² + 12x - 9 = 0

divide through by 3

x² + 4x - 3 = 0

add 3 to each side

x² + 4x = 3

divide 4 in half and square it; add it to each side of equation

x² + 4x + 4 = 3 + 4

(x + 2)² = 7

x + 2 =
`√(7)`

x = -2 ±
`√(7)`