làm giúp tớ câu chẵ KHÔNG LÀM CÂU LẺ

1) (1/(y(x - y))) / (1/(x(x - y))) = x/y

2) (x + 6) / (2x + 6) + (x) / (5x + 5) = 1/2 + 1/5 = 7/10

5) (1/(xy - x^2)) / (1/(y^2 - xy)) = (y^2 - xy)/(xy - x^2) = -(y)/(x)

7) (x + 3) / (x^2 - 1) + (x + 1) / (x^2 - x)
= ((x + 3)(x - 1) + (x + 1)(x + 1)) / ((x^2 - 1)(x^2 - x))
= (x^2 + 2x + 3)/(x^2 - 1)(x - 1)

8) (x + 9) / (x - 9) + (2 + 9) = 12 / (x - 9)

10) (3x + 5) / (x^2 - 5x) + (25 - 5x)/(x^2 - 5x) = 28/(x^2 - 5x)

11) (x + 1)/(2x + 6) + (y)/(5x - 6x) = (x + 1)/2 - y

14) (1/(x + 1)) - (2/(x - 2)) = (x - 2 - 2(x + 1)) / ((x + 1)(x - 2))

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