8. a^2 - 2a - 8=0
(a+2)(a-4)=0
a+2=0 or a-4=0
ANSWER: a=-2 or a=4
9. 2x^2 + 9x + 4 =0
(2x+1)(x+4)=0
2x+1=0 or x+4=0
ANSWER: x=(-1/2) or x=-4
10. 6x^2 - 8x=8
6x^2 - 8x -8 = 0
2(3x+2)(x-2)=0
3x+2=0 or x-2=0
ANSWER: x=(-2/3) or x=2
11. 9x^2 = -18x
9x^2 + 18x =0
9x(x +2) =0
x=0 or x+2=0
ANSWER: x=0 or x=-2
12. 3x^2 +15x = -18
3x^2 +15x + 18 =0
3(x+2)(x+3)
x+2=0 or x+3=0
ANSWER: x=-2 or x=-3
13. 4y^2 - 10y+6=0
2(y-1)(2y-3)=0
y-1=0 or 2y-3=0
ANSWER: y=1 or y=(3/2)
