SOLUTION: In solving the equation (x + 3)(x – 3) = -8, Eric stated that the solution would be x + 3 = -8 => x = -11 or (x – 3) = -8 => x = -5 However, at least one of these solutions fa

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons -> SOLUTION: In solving the equation (x + 3)(x – 3) = -8, Eric stated that the solution would be x + 3 = -8 => x = -11 or (x – 3) = -8 => x = -5 However, at least one of these solutions fa      Log On


   

Question 369288: In solving the equation (x + 3)(x – 3) = -8, Eric stated that the solution would be
x + 3 = -8 => x = -11
or
(x – 3) = -8 => x = -5
However, at least one of these solutions fails to work when substituted back into the original equation. Why is that? Please help Eric to understand better; solve the problem yourself, and explain your reasoning.
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Because the product of %28x-3%29 and %28x%2B3%29+must equal -8
If x-3=8 and x%2B3=-1 at the same time, then it would work.
If x%2B3=-11, then x-3=-17, %28-11%29%28-17%29=187
If x-3=-8, then x%2B3=-2, %28-8%29%28-2%29=16
Neither product is -8.
.
.
%28x%2B3%29%28x-3%29=-8
x%5E2-9=-8
x%5E2=1
highlight%28x=0+%2B-+1%29