Выполнить сложение или вычитание:

а) 4 а^2b / (2a-3) ^2-9b / (3-2a) ^2

b) x^2 / (x-3y) ^3+9y^2 / (3y-x) ^3

c) (yx^2+16 / (y-1) (x-4)) - (16y+x^2 / (xy-x-4y+4))

А) 4 а^2b / (2a-3) ^2-9b / (3-2a) ^2=а) 4 а^2b / (2a-3) ^2-9b / (2a-3) ^2=

(4 а^2b-9b) / (2a-3) ^2=b (4 а^2-9) / (2a-3) ^2 = (b (2a-3) (2a+3)) / (2a-3) ^2 = (b (2a+3)) / (2a-3)

b) x^2 / (x-3y) ^3+9y^2 / (3y-x) ^3=x^2 / (x-3y) ^3-9y^2 / (x-3y) ^3 = (x^2-9y²) / (x-3y) ^3=

(x-3y) (x+3y) / (x-3y) ^3 = (x+3y) / (x-3y) ^2

c) (yx^2+16 / (y-1) (x-4)) - (16y+x^2 / (xy-x-4y+4)) = (yx^2+16 / (y-1) (x-4)) - (16y+x^2 / (y-1) (x-4)) =

(yx^2+16-16y-x^2) / ((y-1) (x-4)) = ((y-1) (x²-16)) / ((y-1) (x-4)) = (x²-16) / (x-4) =

((x-4) (x+4)) / (x-4) = x+4