计算：1x-1-2x2-1=______．

题型：填空题难度：简单来源：广西

计算：

1

x-1

-

2

x2-1

=______．

答案

原式=

x+1

(x-1)(x+1)

-

2

(x-1)(x+1)

=

x+1-2

(x-1)(x+1)

=

x-1

(x-1)(x+1)

=

1

x+1

．