Question

下列公式如何化简呢?2--------- - 2 如何化简x^2+1

Answer 1

2/(x^2+1)-2

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

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

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

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