#1
39x³y/26x²y²=3x/2y
3y/(y²-2y)=3y/y(y-2)=3/(y-2)
(3a-3b)/(a²-b²)=3(a-b)/(a-b)(a+b)=3/(a+b)
(a²-25)/(a²-10a+25)=(a-5)(a+5)/(a-5)²=
(a+5)/(a-5)
#2
(3-2a)/2a-(1-a²)/a²=(3a-2a²-2+2a²)/2a²=
(3a-2)/2a²
1/(3x+y)-1/(3x-y)=(3x-y-3x-y)/(3x+y)(3x-y)=
-2y/(3x+y)(3x-y)
(4-3b)/(b²-2b)+3/(b-2)=(4-3b)/b(b-2)+3/(b-2)=(4-3b+3b)/b(b-2)=4/b(b-2)
#3
1/(x²-4)-1/(x-2)-1/(x+2)=1/(x-2)(x+2)-1/(x-2)-1/(x+2)=(1-x-2-x+2)/(x-2)(x+2)=(1-2x)/(x-2)(x+2)