Question

若m+1/m =3 则m的3次方+m的-3次方=？

rt

Answer 1

把题目化简一下就成了3的2m+6次方乘以3的3m+3次方除以3的m-1次方等于3的4次方！由此可得，（2m+6）+（3m+3）-(m-1)=4
所以m=-1
谢谢采纳！

Answer 2

由m+1/m=3得
(m+1/m)^2=9即m^2+1/m^2+1=9所以m^2+1/m^2=7
又m^3+1/m^3=(m+1/m)(m^2-m*1/m+1/m^2)
得m^3+1/m^3=3*(7-1)=18