SOLUTION: In solving the equation (x + 4)(x � 7) = -24, Eric stated that the solution would be x + 4 = -24 => x = -28 or (x � 7) = -24 => x = -17 However, at least one of these solutions

Question 552386: In solving the equation (x + 4)(x � 7) = -24, Eric stated that the solution would be
x + 4 = -24 => x = -28
or
(x � 7) = -24 => x = -17
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 richard1234(7193) (Show Source): You can put this solution on YOUR website!
Used "zero-property rule" incorrectly.

x^2 - 3x - 28 = -24

x^2 - 3x - 4 = 0

(x+1)(x-4) = 0

Now we use the zero-property rule.

x = -1 or x = 4
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