a)
\(x^3+x^2y-xy^2-y^3=\left(x^3-xy^2\right)+\left(x^2y-y^3\right)\\ =x\left(x^2-y^2\right)+y\left(x^2-y^2\right)=\left(x^2-y^2\right)\left(x+y\right)=\left(x+y\right)^2\left(x-y\right)\)
b)
\(x^3y^2+1-x^2-y^2=\left(x^3y^2-y^2\right)+\left(1-x^2\right)\\ =y^2\left(x^3-1\right)+\left(1-x^2\right)=y^2\left(x-1\right)\left(x^2+x+1\right)-\left(x-1\right)\left(x+1\right)\\ =\left(x-1\right)\left(y^2-x-1\right)\)
c)
\(x^2-y^2-4x+4y=\left(x^2-y^2\right)-4\left(x-y\right)\\ =\left(x-y\right)\left(x+y\right)-4\left(x-y\right)=\left(x-y\right)\left(x+y-4\right)\)
d)
\(x^2-y^2-2x-2y=\left(x^2-y^2\right)-2\left(x+y\right)\\ =\left(x-y\right)\left(x+y\right)-2\left(x+y\right)=\left(x+y\right)\left(x-y-2\right)\)
e)
\(x^3-y^3-3x+3y=\left(x^3-y^3\right)-3\left(x-y\right)\\ =\left(x-y\right)\left(x^2+xy+y^2\right)-3\left(x-y\right)\\ =\left(x-y\right)\left(x^2+xy+y^2-3\right)\)
a ) Cách 2 : \(x^3+x^2y-xy^2-y^3\)
\(=\left(x^3-y^3\right)+xy\left(x-y\right)\)
\(=\left(x-y\right)\left(x^2+xy+y^2\right)+xy\left(x-y\right)\)
\(=\left(x-y\right)\left(x^2+xy+y^2+xy\right)\)
\(=\left(x-y\right)\left(x+y\right)^2\)
b ) Đề đúng : \(x^2y^2+1-x^2-y^2\)
\(=x^2\left(y^2-1\right)-\left(y^2-1\right)\)
\(=\left(x^2-1\right)\left(y^2-1\right)\)
\(=\left(x-1\right)\left(x+1\right)\left(y-1\right)\left(y+1\right)\)
c ) \(x^2-y^2-4x+4y\)
\(=\left(x-y\right)\left(x+y\right)-4\left(x-y\right)\)
\(=\left(x-y\right)\left(x+y-4\right)\)
d ) \(x^2-y^2-2x-2y\)
\(=\left(x-y\right)\left(x+y\right)-2\left(x+y\right)\)
\(=\left(x-y-2\right)\left(x+y\right)\)
e ) \(x^3-y^3-3x+3y\)
\(=\left(x-y\right)\left(x^2+xy+y^2\right)-3\left(x-y\right)\)
\(=\left(x-y\right)\left(x^2+xy+y^2-3\right)\)
