1234567890/(1234567891)2−1234567890×1234567892.

问题描述:

1234567890
(1234567891)2−1234567890×1234567892

设1234567891=A,则1234567890=A-1,1234567892=A+1,
原式=

A−1
A2−(A−1)(A+1)

=
A−1
A2−(A2−1)

=A-1,
=1234567891-1,
=1234567890.