Answer:
f = -3 , 5/2
Step-by-step explanation:
8f² + 4f - 60 = 0
Divide the entire equation by 4
2f² + f - 15 = 0
Product = -30
Sum = 1
Factors = -5 , 6 {(-5)*6 = -30 and -5 +6 = 1}
2f² + f -15 = 0 {Rewrite the middle term using the factors}
2f² + 6f - 5f -15 = 0
2f(f + 3) - 5(f + 3) = 0
(f +3) (2f - 5) = 0
f +3 = 0 ; 2f -5 = 0
f = -3 ; 2f = 5
f = 5/2
