设公比为q,首项为a1,则由a1,二分之一a3,a2成等差数列可得/
a3=a1+a2 即a1*q^2=a1+a1*q
q^2=1+q可求得q=(1+√5)/2
(a3+a2)/(a4+a5)
=(a1*q^2+a1*q^3)/(a1*q^3+a1*q^4)
=(q+1)/(q^2+q)
=1/q
=2/(1+√5)
=(√5-1)/2

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