5x-3y+2x-4y
x^2y+xy+x^2y
x^2+x^2+3x^2
2x^2+3x-5x^2-x+8
3x^2+y^3-x^2-y^3
4y^2-3y^2
4yx^2-3y^2
1+1
Factorize 4x2 - 9y2 + 20x + 25
xy+yx-2xy+1
