Factor by grouping 3r^2+8r-3

Question

Factor by grouping 

Answer 1

3r² + 8r -3

Where

a = 3

b = 8

c = -3

You use the product of a*c = -9

Now ask yourself what factors of -9 could add up to 8?

it's gonna be 9 and -1 so you write that out in place of 8r

3r² + 9r - 1r -3

Now separate your common terms

3r(r + 3) - 1(r+3)

And finally

(3r - 1)(r + 3)