1)3b³/5a, a≠0,b≠0
2)2x/3y, x≠0,y≠0,x≠-y
3)5(m-n)/mn(m-n)=5/mn, m≠0,n≠0,m≠n
4)(4a²-9)/(10a+15)=(2a+3)(2a-3)/5(2a+3)=(2a-3)/5, a≠-3/2
5)(a²+2ab+b²)/(a²-b²)=(a+b)(a+b)//a+b)(a-b)=(a+b)/)a-b), a≠b,a≠-b
6)(x³+1)/(x²+x)=(x+1)(x²-x+1)/x(x+1)=(x²-x+1)/x , x≠0,x≠-1