Question

已知m^2+2m-1=0,求m^2加m的平方分之一的值

Answer 1

由m^2+2m-1=0得

m+2-1/m=0 (两边除以m,显然m不等于0)

m-1/m=-2

平方

(m-1/m)^2=4

展开

m^2-2*m*1/m+1/m^2=4

m^2-2+1/m^2=4

m^2+1/m^2=6.