Help with Factoring? Thanks! ~Bree :) (will post below, explanation needed if possible, thanks!)

Question

bookworm14 · Answer

attachment

welshfella · Answer

2a^2 - 11a + 9
= 2a^2 - 2a - 9a + 9

welshfella · Answer

now you can factor the above by grouping

welshfella · Answer

Hint: take 2a out to factor the first 2 terms

bookworm14 · Answer

how did you know to subtract 2a? (sorry this is on my review and it has completely slipped my mind)

welshfella · Answer

I used the ac method
you multiply the coefficient of x^2 by the last term
here it is  2 * 9 = 18
 i need  2 numbers whose product is + 18 and whose sum =  middle part which is -11
so i write -2x - 9x

welshfella · Answer

- for x  read a

bookworm14 · Answer

ohh okay, i think its coming back to me now, thank you!

welshfella · Answer

yw