1+(1/1+2)+(1/1+2+3)+…+(1/1+2+3+4+…+50)用简便算法第二道.(1/2×3×4)+(1/3×4×5)+(1/4×5×6)+…+(1/8×9×10)用简便算法.还有一道【(5+(1/4)-4.25)×5/8】÷(3/8)
来源:学生作业帮助网 编辑:作业帮 时间:2024/07/05 14:24:49
![1+(1/1+2)+(1/1+2+3)+…+(1/1+2+3+4+…+50)用简便算法第二道.(1/2×3×4)+(1/3×4×5)+(1/4×5×6)+…+(1/8×9×10)用简便算法.还有一道【(5+(1/4)-4.25)×5/8】÷(3/8)](/uploads/image/z/1572319-55-9.jpg?t=1%EF%BC%8B%EF%BC%881%2F1%EF%BC%8B2%EF%BC%89%EF%BC%8B%EF%BC%881%2F1%EF%BC%8B2%EF%BC%8B3%EF%BC%89%EF%BC%8B%E2%80%A6%EF%BC%8B%EF%BC%881%2F1%EF%BC%8B2%EF%BC%8B3%EF%BC%8B4%EF%BC%8B%E2%80%A6%EF%BC%8B50%EF%BC%89%E7%94%A8%E7%AE%80%E4%BE%BF%E7%AE%97%E6%B3%95%E7%AC%AC%E4%BA%8C%E9%81%93.%EF%BC%881%2F2%C3%973%C3%974%EF%BC%89%EF%BC%8B%EF%BC%881%2F3%C3%974%C3%975%EF%BC%89%EF%BC%8B%EF%BC%881%2F4%C3%975%C3%976%EF%BC%89%EF%BC%8B%E2%80%A6%EF%BC%8B%EF%BC%881%2F8%C3%979%C3%9710%EF%BC%89%E7%94%A8%E7%AE%80%E4%BE%BF%E7%AE%97%E6%B3%95.%E8%BF%98%E6%9C%89%E4%B8%80%E9%81%93%E3%80%90%EF%BC%885%EF%BC%8B%281%2F4%29%EF%BC%8D4.25%29%C3%975%2F8%E3%80%91%C3%B7%EF%BC%883%2F8%EF%BC%89)
1+(1/1+2)+(1/1+2+3)+…+(1/1+2+3+4+…+50)用简便算法第二道.(1/2×3×4)+(1/3×4×5)+(1/4×5×6)+…+(1/8×9×10)用简便算法.还有一道【(5+(1/4)-4.25)×5/8】÷(3/8)
1+(1/1+2)+(1/1+2+3)+…+(1/1+2+3+4+…+50)用简便算法
第二道.(1/2×3×4)+(1/3×4×5)+(1/4×5×6)+…+(1/8×9×10)用简便算法.还有一道【(5+(1/4)-4.25)×5/8】÷(3/8)+3.3÷1又5/6每道题都用简便算法,
1+(1/1+2)+(1/1+2+3)+…+(1/1+2+3+4+…+50)用简便算法第二道.(1/2×3×4)+(1/3×4×5)+(1/4×5×6)+…+(1/8×9×10)用简便算法.还有一道【(5+(1/4)-4.25)×5/8】÷(3/8)
第一题1/(1+2+3+----+n)=1/[n(n+1)/2]=2[1/n-1/(n+1)]
1/(1+2)+1/(1+2+3)+1/(1+2+3+4)+……+1/(1+2+3+4+……+50)
=2(1/2-1/3+1/3-1/4+1/4-1/5+-----+1/50-1/51)(消去中间部分)
=2(1/2-1/51)
=49/51
1. 1÷(1+2+3+......+n)=1÷[n(n+1)÷2]=2[1÷n-1÷(n+1)]
1÷(1+2)+1÷(1+2+3)+1÷(1+2+3+4)+......+1÷(1+2+3+4+.....+50)
=2(1÷2-1÷3+1÷3-1÷4+1÷4-1÷5+......+1÷50-1÷51)
=2(1÷2-1÷51)
=49÷51