Thực hiện phép tính: a) 8/[(x^2 + 3)(x^2 - 1)] + 2/(x^2 + 3) + 1/(x + 1); b) (x + y)/[2(x - y)] - (x - y)/[2(x + y)] + 2y^2/(x2 - y^2)

a) 8/(x^2 + 3)(x^2 - 1) + 2/x^2 + 3 + 1/x + 1
b) x + y/2(x - y) - x - y/2(x + y) + 2y^2/x2 - y^2
c) x - 1/x^3 - x + 1/x^3 - x^2 + 3/x^3 - 2x^2 + x
d) xy/ab + (x - a)(y - a)/a(a - b) - (x - b)(y - b)/b(a - b)
e) x^3/x - 1 - x^2/x + 1 - 1/x - 1 + 1/x + 1
f) x^3 + x^2 - 2x - 2x - 20/x^2 - 4 - 5/x + 2 + 3/x - 2