m的平方减5m减1等于0,则2m的平方减5m加（m的平方分之一得多少）

m^2-5m-1=0
m^2=5m+1
原式=10m+2-5m+1/(5m+1)
=5m+2+1/(5m+1)
=(25m^2+15m+3)/(5m+1)
=(125m+25+15m+3)/(5m+1)
=(140m+28)/(5m+1)
=28(5m+1)/(5m+1)
=28