∵x=

4

5 +1

=

4( 5 +1)

( 5 +1)( 5 -1)

=

5

+1，
∴x²+5x-6=（

5

+1）²+5（

5

+1）-6
=5+2

5

+1+5

5

+5-6
=5+7

5

．