Question

已知logx/log3=(-1)/[(log3)/log2],求和x+x的平方+x的3次方+...+x的n次方.

Answer 1

logx/log3=(-1)/[(log3)/log2]

logx=-log2=log(1/2)

x=1/2

原式=1/2*(1-1/2^n)/(1-1/2)=1-1/2^n