3×（1×2+2×3+3×···+99×100）的值为多少?

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3×（1×2+2×3+3×···+99×100）的值为多少?
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3×（1×2+2×3+3×···+99×100）的值为多少?
3×（1×2+2×3+3×···+99×100）的值为多少?

3×（1×2+2×3+3×···+99×100）的值为多少?
=3（1+1+2*2+2+3*3+3+…+99*99+99）
=3[（1+2+3+…+99）+（1+2*2+3*3+…+99*99）]
=3[（1+99）*99/2+99*（99+1）*（2*99+1）/6]
=3*[99*（99+1）*（99+2）/6]
=9900*101/2
=499950

8+11+14+17+20+·······+305 数学计算题.呜呜呜1+2+3+4+···················+98+99+100+99+98+···············+3+2+1 1+2+3+4·······+98+99等于多少 计算1-2+3-4+5-6+······+99-100= 计算：(2+4+6+8+···+100)-(1+3+5+···+99) 1+2+3+······+98+99+100=? 计算1-2+3-4+5-6+······-98+99= 1+2+3+······+95+96+97+98+99=? 急·····················1+2+3+...+999=? 1 2 3 4 ·····7 ·······10 ········?1 3 5 7 ·····?······?··········290 1 4 9 ·····?······?··········? (2+4+6+8+······+100)—(1+3+5+7+······+99)等于几 1+2++3+··········+10000= 观察下列三角形数表其中从第二行起每行的每一个数为其肩膀上两树之和则该表的最后一个数是?1 2 3 4 5 6 7 8················ 97 98 99 100 3 5 7·························· 巧算：100+99-98-97+96+95-·····+4+3-2-1 1+（-2）+3+（-4）···········+99-100等于多少 100+99-98-97+96+95+·······+4+3-2-1怎么做? 1/100+2/100+3/100·······98/100+99/100怎样算? 计算：1-100+2-99+3-98+···+98-3+99-2+100-1 数学题1*2分之一+2*3分之一+3*4分之一+···············+99*100分之一=（ ）