Question

先化简，再求值：x2?1x2?2x+1?x2?2xx2?3x+2÷x，其中x＝2

先化简，再求值：x2?1x2?2x+1?x2?2xx2?3x+2÷x，其中x＝2．

Answer 1

x2?1

x2?2x+1

-

x2?2x

x2?3x+2

÷x
=

(x+1)(x?1)

(x?1)2

-

x(x?2)

(x?1)(x?2)

×

1

x

=

x+1

x?1

-

1

x?1

=

x

x?1

，
当x=

2

时，原式=

2

2 ?1

=

2 ( 2 +1)

( 2 ?1)( 2 +1)

=2+

2

．