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Question 303249: 2a squared-9a-18
this is Factoring Trinomials
Answer by texttutoring(324)   (Show Source):
You can put this solution on YOUR website! First, multiply the first term by the third term, 2*(-18) = -36
You need to find two numbers that multiply to -36, but add up to -9.
List the factors of 36: 36 and 1, 12 and 3, 9 and 4, 6 and 6....
You should notice that 12 and 3 are the only pair that could add up to 9.
Now we will re-write the equation with these factors:
2a^2 -9a - 18
2a^2 - 12a + 3a - 18
Now factor out the 2a from the first pair, and the 3 from the second pair.
2a(a-6) + 3(a-6)
Notice that the (a-6) terms are identical. Now re-arrange, combining the 2a and the 3:
(2a+3)(a-6)
Use F.O.I.L. to check that it is correct. It should equal 2a^2 -9a -18
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