A = 1/x + 1/x-5
A = 1*(x-5) / x(x-5) + 1*x / (x-5)*x
A = x-5+x / x(x-5)
A = 2x-5 / x(x-5)
B = 2/(x+1) + 1/(x-1)
B = 2(x-1) / (x+1)(x-1) + (x+1) / (x-1)(x+1)
B = 2x-2+x+1 / (x+1)(x-1)
B = 3x-1 / (x+1)(x-1)
C = 5/(x+4) - 1/(x-3)
C = 5(x-3) / (x+4)(x-3) - (x+4) / (x-3)(x+4)
C = 5(x-3)-(x+4) / (x+4)(x-3)
C = 5x-15-x-4 / (x+4)(x-3)
D = 3/x - (x+1)/(x-1)
D = 3(x-1)/x(x-1) - x(x+1)/(x-1)x
D = 3(x-1)-x(x+1) / x(x-1)
D = 3x-3-x²-x / x(x-1)
D = -x²+2x-3 / x(x-1)
