Question

Use completing the square to solve for x in the equation (x+7)(x-9)=25

A. x=-4 or 6
B. x=-2 or 14
C. x=1+/- the square root of 89
D. x=1+/- the square root of 87

Answer 1

C

Explanation:

(x+7)(x-9)=25

x^2-2x-63=25

x^2-2x-88=0

(x^2-2x+1)-1-88=0

(x-1)^2=89

x=1 +/- the square root of 89

Hope this helps!

Answer 2

x= 1±√89

Explanation:

(x+7)(x-9)=25

x²-9x+7x-63=25

x²-2x+1- 64=25

(x-1)²= 25+64

(x-1)²=89

x-1= ± √89

x= 1±√89