SOLUTION: solve: (a + 3)(a + 4) = -72 don't understand how the answer is -12,5 I see a^2 + 7a + 12 = 72 a^2 + 7a + 12 + 72 but it's all wrong and I can't seem to figure wher

Algebra ->  Algebra  -> Distributive-associative-commutative-properties -> SOLUTION: solve: (a + 3)(a + 4) = -72 don't understand how the answer is -12,5 I see a^2 + 7a + 12 = 72 a^2 + 7a + 12 + 72 but it's all wrong and I can't seem to figure wher      Log On

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Question 46991: solve:
(a + 3)(a + 4) = -72
don't understand how the answer is -12,5
I see a^2 + 7a + 12 = 72
a^2 + 7a + 12 + 72
but it's all wrong and I can't seem to figure where it was that I went wrong
Answer by mathchemprofessor(65) About Me  (Show Source):
You can put this solution on YOUR website!
If the problem is (a+3)(a+4)=72,on expansion it gives
a^2+7a+12=72
a^2+7a+12-72=0
a^2+7a-60=0
On factoring, we get
(a+12)(a-5)=0
So,either a+12=0 or
a-5=0
Therefore, a=-12 or +5