Question

Answer 1

Bài 3.2: 

\(a,A=x^2+2x-xy-2y\\ =x\left(x+2\right)-y\left(x+2\right)\\ =\left(x-y\right)\left(x+2\right)\\ b,B=xy+7x-5y-35\\ =x\left(y+7\right)-5\left(y+7\right)\\ =\left(x-5\right)\left(y+7\right)\\ c,C=x^2+2x+1-y^2\\ =\left(x^2+2x+1\right)-y^2\\ =\left(x+1\right)^2-y^2\\ =\left(x+1-y\right)\left(x+1+y\right)\\ d,D=x^2y+xy^2+x+y\\ =xy\left(x+y\right)+\left(x+y\right)\\ =\left(xy+1\right)\left(x+y\right)\)

Answer 2