Bài 1A:
\(a,x^2-xy+x-y\\ =x\left(x-y\right)+\left(x-y\right)\\ =\left(x+1\right)\left(x-y\right)\\ b,xz+yz+4x+4y\\ =z\left(x+y\right)+4\left(x+y\right)\\ =\left(x+y\right)\left(z+4\right)\\ c,x^2-x-y^2+y\\ =\left(x-y\right)\left(x+y\right)-\left(x-y\right)\\ =\left(x-y\right)\left(x+y-1\right)\\ d,x^2+2x+2z-z^2\\ =\left(x-z\right)\left(x+z\right)+2\left(x+z\right)\\ =\left(x+z\right)\left(x-z+2\right)\)
Bài 1B:
\(a,x^2+2xy+x+2y\\ =x\left(x+2y\right)+\left(x+2y\right)\\ =\left(x+2y\right)\left(x+1\right)\\ b,2xy+yz+2x+z\\ =y\left(2x+z\right)+\left(2x+z\right)\\ =\left(y+1\right)\left(2x+z\right)\\ c,y^2-2y-z^2-2z\\ =\left(y-z\right)\left(y+z\right)-2\left(y+z\right)\\ =\left(y+z\right)\left(y-z-2\right)\\ d,x^3-x-y+y^3\\ =\left(x+y\right)\left(x^2-xy+y^2\right)-\left(x+y\right)\\ =\left(x+y\right)\left(x^2-xy+y^2-1\right)\)
1B
a)
\(=x\left(x+2y\right)+\left(x+2y\right)\\ =\left(x+1\right)\left(x+2y\right)\)
b)
\(=y\left(2x+z\right)+\left(2x+z\right)\\ =\left(y+1\right)\left(2x+z\right)\)
c)
\(=\left(y^2-z^2\right)-\left(2y+2z\right)\\ =\left(y-z\right)\left(y+z\right)-2\left(y+z\right)\\ =\left(y+z\right)\left(y-z-2\right)\)
d)
\(=\left(x^3+y^3\right)-\left(x+y\right)\\ =\left(x+y\right)\left(x^2-xy+y^2\right)-\left(x+y\right)\\ =\left(x+y\right)\left(x^2-xy+y^2-1\right)\)
