已知:m+1/m=5,则m²+1/m²= ,m3+1/m3=

问题描述:

已知:m+1/m=5,则m²+1/m²= ,m3+1/m3=

∵m+1/m=5
 ∴m²+1/m²
  =(m+1/m)²-2
  =25-2
  =23
 ∴m³+1/m³
  =(m+1/m)(m²+1/m²-1)
  =5×(23-1)
  =5×22
  =110