Question

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 1

Remember:
\[(a+b)(a-b) = a^2 - b^2\]

Using this:

\[x^2 - 9 = -8\]

Or,

\[x^2 = 1\]

Here you can find x and that will be your answer...

Answer 2

thnaks

Answer 3

Welcome dear...