Question

Complete the square to solve the equation below.

x² + 2x-7= 17
A. x = -1, x = 4
O B. X=-6, x = 4
O C. X=-1, x = 3
O D. x = 5, x= -4
SUBM

Answer 1

9514 1404 393

Answer:

B. x = -6, x = 4

Explanation:

The constant on the left wants to be 1, the square of half the x-coefficient. We can get it to be that value by adding 8 to the equation.

x² +2x +1 = 25

(x +1)² = 25 . . . . . . . rewrite the left side as a square

x +1 = ±√25 = ±5 . . . . take the square root

x = -1 ±5 . . . . . . . . . subtract 1

x = -6 or x = 4