Answer:
5a^2 + 4a - 9 = (5a + 9)(a - 1)
Step-by-step explanation:
The given expression is 5a^2 + 4a - 9
The leading coefficient is 5 and last term is -9
Multiply them, we get -45
Now find the factors of -45 such that when you add the factors we have to get 4.
9*-5 = -45
9 + (-5)= 4
The right factors are 9 and -5.
5a^2 + 4a - 9 = 5a^2 + 9a - 5a - 9
= 5a^2 - 5a + 9a - 9
= 5a(a -1)+9(a-1)
= (5a +9)(a-1)
The missing factor is (a -1)
Thank you.