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1/2+1/6+1/12+1/20+…+1/90
用简便方法计算:
1/2+1/6+1/12+1/20+…+1/90
答:
1/2+1/6+1/12+1/20+…+1/90 =
1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7+1/7-1/8+1/8-1/9+1/9-1/10 =1-1/10 =9/10(10分之9)朋友,请【采纳答案】,您的采纳是我答题的动力,谢谢。
1/2+1/6+1/12+1/20+
...
+1/90
简便计算。
答:
答:
1/2+1/6+1/12+1/20+
...
+1/90
=1/2+(1/2-1/3)+(1/3-1/4)+(1/4-1/5)+...+(1/9-1/10)=1/2+1/2-1/10 =1-1/10 =9/10
1/2+1/6+1/12+1/20+
.
+1/90
的答案是多少
答:
1/2+1/6+1/12+1/20+...+1/90 =1/(1×2)+1/(2×3)+1/(3×4)+1/(4×5)+...+1/(9×10)=
1-1/2+1/2-1/3+1/3
-1/4+1/4-1/5+...+1/9-1/10 =1- 1/10 =9/10 总结:1、本题是拆项法的典型习题。2、拆项方法:1/[n(n+1)]=1/n -1/(n+1)3、推...
1/2+1/6+1/12+1/20+……+1/90
=
答:
分析:1/2=1-1/2,1/6=1/2-1/3,1/12=1/3-1/4。。。1/90=1/9-1/10
1/2+1/6+1/12+1/20+……+1/90 =1-1/2+1/2-1/3+1/3-。。。-1/9+1/9-1/10 =1-1/10 =9/10
1/2+1/6+1/12+1/20+
...
+1/90
=?
答:
这个问题,首先要看到 1/2=1/(1*2)1-1/2 1/6=1/(2*3)=1/2-1/3 1/12=1/(3*4)=1/3-1/4 ```1/90=1/(9*10)=1/9-1/10 所以
1/2+1/6+1/12+1/20+
...
+1/90
=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/6-1/7…
…+1/
9-1/10 =1-1/10 =9/10 ...
1/2+1/6+1/12+1/20+
...
+1/90
的答案是多少?最好有过程。
答:
1/2+1/6+1/12+1/20+
1/30+...+1/72
+1/90
= 1/1*2 +1/2*3 +1/3*4 +...+1/8*9 +1/9*10 = (1/1 -1/2)+(1/2 -1/3)+...+(1/8 -1/9)+(1/9 -1/10)= 1/1 -1/10 = 9/10
1/2+1/6+1/12+1/20+
⋯
+1/90
答:
1/2+1/6+1/12+1/20+
⋯
+1/90
=1-1/2+1/2-1/3+1/3-1/4
+……+1/
9-1/10 =1-1/10 =9/10
1/2+1/6+1/12+1/20+
...
+1/90
这道算式如何简便计算?
答:
1/2+1/6+1/12+1/20+
...
+1/90
=1/2+(1/2-1/3)+(1/3-1/4)...+(1/9-1/10)=1/2+1/2-1/10 =9/10
计算
1/2+1/6+1/12+1/20
...
1/90
答:
1/2+1/6+1/12+1/20
...
1/90
=(1-1/2)+(1/2-1/3)+(1/3-1/4)
+……+
(1/9-1/10)=1-1/10 =9/10
1/2+1/6+1/12+1/20+
...
1/90
答:
∵1/2=1/1-1/2 1/6=1/2-1/3 1/12=1/3-1/4
……1/90
=1/9-1/10 ∴两边相加,得
1/2+1/6+1/12+1/20+
...+.1/90 =1-1/10=9/10
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