Question

Use completing the square to solve this quadratic equation.

Check all that apply.
x2 + 6x + 9 = 2
A. x = 3 + 4/5
B. x= -3 +2
c. x= 3 - 5
D. =-3-

Answer 1

Explanation:

x² + 6x + 9 = 2

(x + 3)² = 2

x + 3 = ±sqrt(2)

x = -3 ± sqrt(2)

so, B and D are correct.

control :

(-3 + sqrt(2))² + 6(-3 + sqrt(2)) + 9 = 2

9 + 2 - 6sqrt(2) - 18 + 6sqrt(2) + 9 = 2

2 = 2

correct

(-3 - sqrt(2))² + 6(-3 - sqrt(2)) + 9 = 2

9 + 2 + 6sqrt(2) - 18 - 6sqrt(2) + 9 = 2

2 = 2

correct

(3 + sqrt(2))² + 6(3 + sqrt(2)) + 9 = 2

9 + 2 + 6sqrt(2) + 18 + 6sqrt(2) + 9 = 2

38 + 12sqrt(2) = 2

wrong.

(3 - sqrt(2))² + 6(3 - sqrt(2)) + 9 = 2

9 + 2 - 6sqrt(2) + 18 - 6sqrt(2) + 9 = 2

38 - 12sqrt(2) = 2

wrong.