Answer:
x = 1 ±√89
Step-by-step explanation:
Expand (X+ 7)(x-9) = 25:
x^2 + 7x - 9x - 63 = 25
This becomes:
x^2 - 2x - 63 = 25, or
x^2 - 2x = 88
To complete the square: Take half of the coefficient of x (which is -2), and square the result, obtaining +1.
Add +1 to both sides:
x^2 - 2x + 1 = 88 + 1 = 89
Rewriting x^2 - 2x +1 as the square of the binomial x - 1:
(x - 1)^2 = 89
Taking the sqrt of both sides:
x - 1 = ±√89
Solve for x. Add 1 to both sides:
x = 1 ±√89
