SOLUTION: Factor by grouping (sometimes called the ac-method). 5x^2-x-6

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Question 1026580: Factor by grouping (sometimes called the ac-method).
5x^2-x-6
Found 2 solutions by stanbon, ikleyn:
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Factor by grouping (sometimes called the ac-method).
5x^2-x-6
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ac = 5*-6 = -30
b = -1
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Note:: -6*5 = -30 ; -6 + 5 = -1
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Rewrite the problem::
5x^2 - 6x+5x - 6
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Factor the groups::
x(5x-6) + 1(5x-6)
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Factor by groups::
(5x-6)(x+1)
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Cheers,
Stan H.


Answer by ikleyn(52792) About Me  (Show Source):
You can put this solution on YOUR website!
.
Factor by grouping (sometimes called the ac-method).
5x^2-x-6
~~~~~~~~~~~~~~~~~~~~~~~~~~~ 

Simple trick: I will present 6 = 5 + 1, and then . . . 

5x%5E2+-+x+-+6 = 5x%5E2+-+x+-+5+-+1 = %285x%5E2-5%29+-+%28x%2B1%29 = 5%2A%28x%5E2-1%29+-+%28x%2B1%29 = 5*(x-1)*(x+1) - (x+1) = (x+1)*(5x-5-1) = (x+1)*(5x-6). 

Done.