Question

m平方-5m-1=0,求（m四次方+1）/m平方的值

Answer 1

m^2-5m-1=0

→m^2-1=5m

两边平方

→m^4-2m^2+1=25m^

→m^4+1=27m^2

→（m^4+1）/m^2=27