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a)(1000+1):11
=1001:11
=91
91=7.13
b)142+52+22
=196+25+4
=221+4
=225
225=32.52
c)333:3+225:152
=333:3+225:225
=111+1
=112
112=24.7
tớ làm đầy đủ li-ke cho tớ nha
![](https://rs.olm.vn/images/avt/0.png?1311)
(1000+1):11=1001:11=91=7.13
142+52+22=196+25+4=225=32.52
29.31+144:122=899+144:144=899+1=900=22.32.52
333:3+225:152=111+225:225=111+1=112=24.7
ĐÚNG THÌ
KHÔNG ĐÚNG THÌ KHÔNG SAO
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{999}{1000}+\frac{998}{1000}+......+\frac{1}{1000}\)
\(=\frac{999+998+997+........+1}{1000}\)
\(=\frac{499500}{1000}=\frac{999}{2}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
1/1000 + ... + 997/1000 + 998/1000 + 999/1000 = ( 1 + ... + 997 + 998 + 999 ) / 1000 = 499500/1000 = 4995/10
![](https://rs.olm.vn/images/avt/0.png?1311)
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\(\frac{2}{3}+\frac{1}{3}=1=\frac{2}{2}\)
\(\frac{3}{4}+\frac{2}{4}+\frac{1}{4}=\frac{6}{4}=\frac{3}{2}\);
\(\frac{4}{5}+\frac{3}{5}+\frac{2}{5}+\frac{1}{5}=2=\frac{4}{2}\)
;\(\frac{5}{6}+\frac{4}{6}+\frac{3}{6}+\frac{2}{6}+\frac{1}{6}=\frac{15}{6}=\frac{5}{2}\)
Tổng quát:
\(\frac{n-1}{n}+\frac{n-2}{n}+...+\frac{2}{n}+\frac{1}{n}\)(\(n\in N\)) \(=\frac{n-1}{2}\)
Áp dụng:
\(\frac{999}{1000}+\frac{998}{1000}+\frac{997}{1000}+...+\frac{1}{1000}=\frac{999}{2}\).
Xem bài mình đúng không?
![](https://rs.olm.vn/images/avt/0.png?1311)
a)
\(=1001:11=91\)
b)
\(=196+25+4=200+25=225\)
c)
\(=29.31+144:144=899+1=900\)
d)
\(=111+225:225=111+1=112\)
= 1001 : 11
= 91
= 7 . 13
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