-10n+2分之n(n-1)×4=54

问题描述:

-10n+2分之n(n-1)×4=54

-10n+2分之n(n-1)×4=54

-10n+2n²-2n=54

n²-6n-27=0

(n+3)(n-9)=0

n=-3或n=9