Question

先化简，再求值：

x2+2x

1+x

÷(x-

2

x+1

)，其中x=2．

Answer 1

原式=

x2+2x

1+x

÷(x-

2

x+1

)
=

x(x+2)

x+1

÷

x2+x-2

x+1

=

x(x+2)

x+1

×

x+1

(x+2)(x-1)

=

x

x-1

当x=2时，原式=

x

x-1

=

2

2-1

=2．