7. х²-1=(x-1)(x+1)
8.3a²-6ab+3b²=3(a²-2ab+b²)=3(a-b)²
9.x²(x-3)-2x(x-3)+(x-3)=(x-3)×(x²-2x+1)=(x-3)(x-1)²
10. 9y²-25=0
9y²=25
y²= 25/9
y=+-25
y=+- 5/3
y1=5/3 y2=-5/3
7. х²-1=(x-1)(x+1)
8.3a²-6ab+3b²=3(a²-2ab+b²)=3(a-b)²
9.x²(x-3)-2x(x-3)+(x-3)=(x-3)×(x²-2x+1)=(x-3)(x-1)²
10. 9y²-25=0
9y²=25
y²= 25/9
y=+-25
y=+- 5/3
y1=5/3 y2=-5/3