1) x² + 7x = 0
x(x+7) = 0
x=0 ; x=-7
2) 6s² + 18s = 0
6s(s+3) = 0
s=0 ; s=-3
3) t² + 8t + 16 = 0
(t+4)(t+4) = 0
t=4
4) x² -10x +25 = 0
(x-5)(x-5) = 0
x=5
5) h² +6h =16
h² +6h -16 = 0
(h+8)(h-2) = 0
h=-8 ; h=2
6) x² -5x -14 = 0
(x-7)(x+2) = 0
x=7 ; x=-2
7) 11r +15 = -2r²
2r² +11r +15 = 0
(2r+5)(r+3)= 0
r=-5/2 ; r=3
8) x² -25 = 0
(x-5)(x+5)=0
x=5 ; x=-5
9) 81 - 4x² = 0
(9-2x)(9+2x)=0
x=9/2 ; x=-9/2
10) 4s² +9 = 12s
4s² -12s +9=0
(2s-3)(2s-3)=0
s=3/2
d) by equating all the factors to 0
e) Zero product property. Since each of the polynomials may be equated to 0, then at least of their factors is equal to 0.
