1/x+y и 1/y-x

Общий знаменатель: (x+y)(y-x)

1/x+y = (y-x)/(x+y)(y-x) = (y-x)/(x^2-y^2)

1/y-x = (x+y)/(x+y)(y-x) = (x+y)/(x^2-y^2)

a/p-q и a/p+q

Общий знаменатель: (p-q)(p+q) = p^2 - q^2

a/p-q = a(p+q)/(p^2 - q^2) = a(p+q)/(p-q)(p+q) = a/(p-q)

a/p+q = a(p-q)/(p^2 - q^2) = a(p-q)/(p-q)(p+q) = a/(p+q)

3/2x-2y и 5/3x-3y

Общий знаменатель: 6(x-y)

3/2x-2y = 3*3(x-y)/(6(x-y)) = 9(x-y)/6(x-y) = 3/2

5/3x-3y = 5*2(x-y)/(6(x-y)) = 10(x-y)/6(x-y) = 5/3