Question

求证题9.15设等比数列a1,a2,.,an的公比是q,求证如图

Answer 1

an=a1q^(n-1);

a1a2a3...an=a1*(a1q)*(a1q^2)*...*(a1q^(n-1))=a1^n*q^(1+2+...+(n-1))

q的指数是一个等差数列.

得证;