(1*2*4+2*4*8+`````+n*2n*4n/1*3*6+2*6*12+````+n*3n*6n)^2
(1*2*4+2*4*8+`````+n*2n*4n/1*3*6+2*6*12+````+n*3n*6n)^2
数学人气：586 ℃时间：2020-03-29 04:45:34
优质解答
∵1*2*4+2*4*8+`````+n*2n*4n=1*2*4(1+2^3+...+n^3)1*3*6+2*6*12+````+n*3n*6n=1*3*6(1+2^3+...+n^3)∴(1*2*4+2*4*8+`````+n*2n*4n/1*3*6+2*6*12+````+n*3n*6n)^2=(1*2*4/1*3*6)^2=16/81
我来回答
类似推荐