1/(1*2*3)+1/(2*3*4)+1/(3*4*5)+.1/(26*27*28)=?
来源:学生作业帮 编辑:作业帮 分类:数学作业 时间:2024/08/31 17:27:37
1/(1*2*3)+1/(2*3*4)+1/(3*4*5)+.1/(26*27*28)=?
1/(1*2*3)=1/2*[1/1*2-1/2*3]=1/2*[(1/1-1/2)-(1/2-1/3)]=1/2*[1/1-2/2+1/3]
1/(2*3*4)=1/2*[1/2*3-1/3*4]=1/2*[(1/2-1/3)-(1/3-1/4)]=1/2*[1/2-2/3+1/4]
1/(3*4*5)=1/2*[1/3*4-1/4*5]=1/2*[(1/3-1/4)-(1/4-1/5)]=1/2*[1/3-2/4+1/5]
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1/(26*27*28)=1/2*[1/26*27-1/27*28]=1/2*[(1/26-1/27)-(1/27-1/28)]=1/2*[1/26-2/27+1/28]
1/(1*2*3)+1/(2*3*4)+1/(3*4*5)+.+1/(26*27*28)
=1/2*{[1/1-2/2+1/3]+*[1/2-2/3+1/4]+[1/3-2/4+1/5]+...+[1/26-2/27+1/28]}
=1/2*{1-1/2-1/27+1/28}
=1/2*377/756
=377/1512
1/(2*3*4)=1/2*[1/2*3-1/3*4]=1/2*[(1/2-1/3)-(1/3-1/4)]=1/2*[1/2-2/3+1/4]
1/(3*4*5)=1/2*[1/3*4-1/4*5]=1/2*[(1/3-1/4)-(1/4-1/5)]=1/2*[1/3-2/4+1/5]
.
1/(26*27*28)=1/2*[1/26*27-1/27*28]=1/2*[(1/26-1/27)-(1/27-1/28)]=1/2*[1/26-2/27+1/28]
1/(1*2*3)+1/(2*3*4)+1/(3*4*5)+.+1/(26*27*28)
=1/2*{[1/1-2/2+1/3]+*[1/2-2/3+1/4]+[1/3-2/4+1/5]+...+[1/26-2/27+1/28]}
=1/2*{1-1/2-1/27+1/28}
=1/2*377/756
=377/1512
28×(6/7+3/4)+5 1/4×1 2/7÷27简便运算
简算 (1-1/2+1/3-1/4+1/5-1/6+...+1/49-1/50)/(1/26+1/27+...+1/50
1:1 2 5 3 4 19 5 6 )2:21 26 23 24 25 22 27 )3:8 2 -2 -4 -4 )
算24点:(1)3、3、17、27;(2)1、10、14、16;(3)2、5、8、28;(4)3、9、14、21;(5)
(1)1+1/2+1/3+1/4+1/5+1/6+1/7+1/14+1/28
1/(1*3)+1/(2*4)+1/(3*5)+1/(4*6)+...+1/(8*10)=?
(1)1+2+1=4;1+2+3+2+1=_______;1+2+3+4+3+2+1=_______;1+2+3+4+5
1/6【1/4{1/3(1/2X-1)+3}+5】=1
请问7(2X-1)-3(4X-1)-5(3X+2)+27=0
(1)0.4-(-4/1)+6/1(2)3/1-(-6/5)+3/2(3)3/1+(-5/1)+1+3/2(4)27-1
0.25^(-1)*(根号3/2)^(1/2)*(27/4)^(1/4)+log2(1/5)*log3(1/8)*log
(1/3+2/3)+(1/4+2/4+3/4)+(1/5+2/5+3/5+4/5)+.+(1/100+.99/100)=