Câu 2
a, 5ax-10ay= 5a(x-2y)
b, x²-xy +2x-2y
=x(x-y)+2(x-y)= (x-y)(x+2)
c,x²-xy+x-y
=x(x-y)+x-y=(x-y)(x+1)
d, x²-4x-y²+4
=x²-4x+4-y²
=(x-2)²-y²=(x-2-y)(x-2+y)
e, x²+x-2
= x²-x+2x-2
=x(x-1)+2(x-1)
=(x-1)(x+2)
f, 2x²-5x-7
=2x²+2x-7x-7
=2x(x+1)-7(x+1)
=(x+1)(2x-7)