Question

Solve x ^2 + 9x + 8 = 0 by completing the square. What are the solutions?

Answer 1

-1 and -8

Explanation:

x^2+2*9/2*x+(9/2)^2-(9/2)^2+8=0

(x+9/2)^2+32/4-81/4=0

(x+9/2)^2-49/4=0

(x+9/2)^2=(7/2)^2

so

x+9/2=7/2

x=7/2-9/2

x=-2/2

x=-1

or

x+9/2=-7/2

x=-7/2-9/2=-16/2

x=-8