已知:1^2+2^2+3^2+……+n^2 =n(n+1)(2n+1)/6 —① 那么1^2+2^2+3^2+……+n^2+……+（2n+1）^2 =(2n+1)(n+1)(4n+3)/3 —② 又有2^2+4^2+6^2+……+(2n)^2 =4[1^2+2^2+3^2+……+n^2]=4*①=2n(n+1)(2n+1)/3 —③ 设所求...