x/x-1 + 3/x+1 – x^2+1/x^2-1

2 bình luận về “x/x-1 + 3/x+1 – x^2+1/x^2-1”

1. x/(x – 1) + 3/(x + 1) – (x^2 + 1)/(x^2 – 1)

   = x/(x – 1) + 3/(x + 1) – (x^2 + 1)/((x – 1)(x + 1))

   = (x(x + 1))/((x – 1)(x + 1)) + (3(x – 1))/((x + 1)(x – 1)) – (x^2 + 1)/((x – 1)(x + 1))

   = (x^2 + x + 3x – 3 – x^2 + 1)/((x – 1)(x + 1))

   = (4x – 2)/((x – 1)(x + 1))

   Trả lời
2. x/(x-1) + 3/(x+1) – (x^2+1)/(x^2-1)

   = [x.(x+1)]/[(x-1).(x+1) + [3.(x-1)]/[(x+1).(x-1)] – (x^2+1)/(x^2-1)

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

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

   = [(x^2-x^2) + (x+3x) + (-3+1)]/(x^2-1)

   = (4x-2)/(x^2-1)

   = (4x-2)/[(x-1)(x+1)

    

   Trả lời