x-y/(y-x)³ =-(y-x)/(y-x)³=-1/(y-x)²
18a²b(b-a)/24ab²(a-b) =-3a/4b
a²+4a+4/4-a² =(a+2)²/(a+2)(a-2)=(a+2)/(a-2)
4a²-6ab/4a²-12ab+9b²=2a(2a-3b)/(2a-3b)²=2a/(2a-3b)
x-y/(y-x)³ =-(y-x)/(y-x)³=-1/(y-x)²
18a²b(b-a)/24ab²(a-b) =-3a/4b
a²+4a+4/4-a² =(a+2)²/(a+2)(a-2)=(a+2)/(a-2)
4a²-6ab/4a²-12ab+9b²=2a(2a-3b)/(2a-3b)²=2a/(2a-3b)