4 - x^2
x-xm+xp
3-6xy+9xz
25m^2-16n^2
36-12x+x^2
xy+xz-y-z
(x+y) + (x+y)w
(2+x)(2-x)
x(1-m+p)
(x-1)(y+z)
(6-x)^2
3 (1-2xy+3xz)
(5m+4n)(5m-4n)
(x+y)(1+w)
