计算:1×2+2×4+3×6+…+1005×2010=_.
计算:1×2+2×4+3×6+…+1005×2010=______.
数学人气:332 ℃时间:2020-04-10 14:45:06
优质解答
1×2+2×4+3×6+…+1005×2010=1×1×2+2×2×2+3×3×2+…+1005×1005×2;=2×(1×2+2×2+3×2+…+1005×2),=2×[1005×(1005+1)×(1005×2+1)÷6],=2×(1005×1006×2011÷6),=2×(2033181330÷6),...
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