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2-1/2-(-3/4)+(-5/6)-2/3怎么解?求过程

为-50 第一种解法: 1-2+3-4+5-6+……+99-100 =(1-2)+(3-4)+(5-6)+……+(97-98)+(99-100) =(-1)X100/2=-50 解释:原100个数,因从第一项起每相邻两个数相加为-1,所以就变成(100个数/2)=50组数,即50个-1。所以为-50。 第二种解法: 用等差数列求...

等差数列问题,2017*(1+2017)/2 1+2+3+.....2015+2016+2017--① 2017+2016+2015+...+3+2+1--② 由(①+②)/2

设(1-1/2-1/3-1/4-1/5)为a,(1/2+1/3+1/4+1/5)为b,代入得转化为a(b+1/6)-(a-1/6)b,得到ab+1/6a-ab+1/6b,化简为1/6(a+b),再重新代入,解得1/6(1-1/2-1/3-1/4-1/5+1/2+1/3+1/4+1/5)=1/6*1=1/6

4/5+2/3÷(5/6-1/2) =4/5+2/3÷(5/6-3/6) =4/5+2/3÷1/3 =4/5+2 =2又4/5

6/5*(-1/3-1/2)÷5/4 =6/5*(-5/6)×4/5 =-1*4/5 =-4/5 5/7÷(-2又2/5)-5/7*5/12-5÷3/4 =5/7×(-5/12)-5/7*5/12-5×4/3 =-25/84-25/84-20/3 =-25/42-6又2/3 =-7又11/42

解: 原式 =17又3/4-(5又5/6+9又2/3+3又1/2) =17又3/4-(5又10/12+9又8/12+3又6/12) =17又3/4-17又24/12 =17又3/4-19 =-1又1/4

按照四则运算先乘除 前面括号内算下来是5/4 后面括号里面(-1/2)2 理解为(-1/2)×2 即等于(-1) 所以(5/4)÷(-1)=(-5/4) -5/4

=(1-1/2)+(1-1/3)+...(1-1/10) =9-(1/2+1/3+...1/10) =9-[1/2+1/3+1/4+1/5+1/6+1/7+1/8+1/9+1/10] =9-[(1/2+1/3+1/6)+(1/4+1/5+1/10)+1/7+1/8+1/9] =9-(1+11/20+1/8+1/7+1/9) =9-(1+27/40+1/9+1/7) =9-(1+283/360+1/7) =8-2341/2520

以两组为一组得到: 1-2=-1 3-4=-1 5-6=-1 ...... 当n为偶数时 则共n/2项 1-2+3-4+5-6…+(-1)的(n+1次方)n=-1*n/2= - n/2 当n为奇数时 则共(n-1)/2项 1-2+3-4+5-6…+(-1)的(n+1次方)n =-(n-1)/2+n =(-n+1+2n)/2 =(n+1)/2 这题主要是根据n的奇偶...

int k=-1,s=0; for(int i=1;i

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