Question

factor the trinomial 4r^2+4r-15

Answer 1

4r^2+4r-15

= 4r^2+10r-6r-15

= 2r(2r+5)-3(2r+5)

= (2r+5)(2r-3)

Factoring the given trinomial is (2r+5)(2r-3).

2r+5 = 0 and 2r-3 = 0

2r = -5            2r = 3

r = -5/2             r = 3/2