三个数1/m,1,1/n成等差数列,又m^2,1,n^2成等比数列,则(m^2+n^2)/(m+n)的值为?
1/m+1/n=2
m^2*n^2=(mn)^2=1
(m+n)/mn=2
mn=±1
m+n=±2
mn/(m+n)=1/2
(m^2+n^2)/(m+n)=[(m+n)^2-2mn]/(m+n)
=(m+n)-2mn/(m+n)
=±2-2(1/2)
=±2-1
=1或-3
三个数1/m,1,1/n成等差数列,又m^2,1,n^2成等比数列,则(m^2+n^2)/(m+n)的值为?
1/m+1/n=2
m^2*n^2=(mn)^2=1
(m+n)/mn=2
mn=±1
m+n=±2
mn/(m+n)=1/2
(m^2+n^2)/(m+n)=[(m+n)^2-2mn]/(m+n)
=(m+n)-2mn/(m+n)
=±2-2(1/2)
=±2-1
=1或-3