Question

9.

Solve the equation by completing the square. Round to the nearest hundredth if necessary. x2 + 2x = 15

A. 3, –5
B. 3.74, 4
C. 4, –4
D. 15, –17

Answer 1

x = 3 , x = -5

Explanation:

Given x^2 +2x=15 add 1 to both sides to get:

x^2 + 2x + 1 =16

(x+1)^2 = 16

x + 1 = ±
`√(16)` = ± 4

x = -1 ± 4

x = 3 or x = -5