Câu hỏi của hoàng thị thanh trà

Question

a) x-xy+y-y²

b)x²-4x-y²+4

c)x²-2x-3

lý canh hy · Accepted Answer

a, $x-xy+y-y^2=x\left(1-y\right)+y\left(1-y\right)$

$=\left(1-y\right)\left(x+y\right)$

b,$x^2-4x-y^2+4=\left(x^2-4x+4\right)-y^2$

$=\left(x-2\right)^2-y^2=\left(x-2+y\right)\left(x-2-y\right)$

c,$x^2-2x-3=x^2-3x+x-3=x\left(x-3\right)+\left(x-3\right)=\left(x-3\right)\left(x+1\right)$

Câu trả lời:

a, $x-xy+y-y^2=x\left(1-y\right)+y\left(1-y\right)$

$=\left(1-y\right)\left(x+y\right)$

b,$x^2-4x-y^2+4=\left(x^2-4x+4\right)-y^2$

$=\left(x-2\right)^2-y^2=\left(x-2+y\right)\left(x-2-y\right)$

c,$x^2-2x-3=x^2-3x+x-3=x\left(x-3\right)+\left(x-3\right)=\left(x-3\right)\left(x+1\right)$