1、
=1/3×100×101×102=343400
2、
1×2+2×3+…+n(n+1)
= 1/3×(1×2×3-0×1×2)+……+1/3×[n(n+1)(n+2)-(n-1)n(n+1)]
= 1/3×[n(n+1)(n+2)--0×1×2
=n(n+1)(n+2)/3
3、
1×2+2×3+…+1000×1001=1/3×...
1、
=1/3×100×101×102=343400
2、
1×2+2×3+…+n(n+1)
= 1/3×(1×2×3-0×1×2)+……+1/3×[n(n+1)(n+2)-(n-1)n(n+1)]
= 1/3×[n(n+1)(n+2)--0×1×2
=n(n+1)(n+2)/3
3、
1×2+2×3+…+1000×1001=1/3×...