Question

3/4×5/2+1/4×2/5×（1-1/3）等于多少

3/4×5/2+1/4×2/5×（1-1/3）等于多少3/4×5/2+1/4×2/5（1-1/3）等于多少？

Answer 1

1×2+2×3+3×4+...+n(n+1) =1×(1+1)+2×(2+1)+3×(3+1)+...+n(n+1) =12+22+32+...+n2+1+2+3+...+n =n(n+1)(2n+1)/6+n(n+1)/2 =n(n+1)(2n+1+3)/6 =2n(n+1)(n+2)/6 =n(n+1)(n+2)/3 1×2×3+2×3×4+...+7×8×9 =1×(1+1)(1+2)+2×(2+1)(2+2)+...+7×(7+1)(7+2) =13+3×12+2×1+23+3×22+2×2+...+73+3×72+2×7 =(13+23+...+73)+3(12+22+...+72)+2(1+2+...+7) =[(7×8)/2]2+3×7×8×15/6+7×8 =784+420+56 =1260

Answer 2

3/4×5/2+1/4×2/5×（1-1/3）
=15/8+1/10×2/3
=15/8+20/3
=45/24+160/24
=205/24

Answer 3

，.双色球开奖结果