1.7x²-13x+6=(7x²-7x)-(6x-6)=7x(x-1)-6(x-1)=(7x-6)(x-1)
2.15x²+7xy-4y²=(15x²-5xy)+(12xy-4y²)=5x(3x-y)+4y(3x-y)=(3x-y)(5x+4y)
3.-y²-4y+12=(-y²-6y)+(12+2y)=-y(6+y)+2(6+y)=(6+y)(2-y)
4.x²-(a+1)x+a=(x²-ax)-(x-a)=x(x-a)-(x-a)=(x-a)(x-1)
1.7x²-13x+6=(7x²-7x)-(6x-6)=7x(x-1)-6(x-1)=(7x-6)(x-1)
2.15x²+7xy-4y²=(15x²-5xy)+(12xy-4y²)=5x(3x-y)+4y(3x-y)=(3x-y)(5x+4y)
3.-y²-4y+12=(-y²-6y)+(12+2y)=-y(6+y)+2(6+y)=(6+y)(2-y)
4.x²-(a+1)x+a=(x²-ax)-(x-a)=x(x-a)-(x-a)=(x-a)(x-1)