Factor 2a^2-9a-5

Question

what is the answer to

factor the following expression:

2a^2-9a-5

Answer 1

Hello Mack,

 

The answer to your question is (2a + 1)(a - 5). That being said, these types of problems become easier and more intuitive with much practice, which is what I suggest.

 

When looking at this through the F.O.I.L. method (first, outside, inside, last...is factoring still taught this way in school?), I typically start with the two ends "F" and "L" and then figure out the middle.

 

Because the number 5 in the expression above is negative and prime, you know that it must be a product of either +5 and -1 or -5 and +1. In the same way, you can only get to 2a² by either multiplying (2a)*(a) or (-2a)*(-a). With this information, only the grouping needs to be determined in order to give you -9a in the middle. I hope this helped!

 

Best,

- Avery