\(A=\frac{1}{18}+\frac{1}{36}+\frac{1}{60}+\frac{1}{90}+\frac{1}{126}+\frac{1}{168}\)
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Những câu hỏi liên quan
\(\frac{1}{6}\)+\(\frac{1}{18}\)+\(\frac{1}{36}\)+\(\frac{1}{60}\)+\(\frac{1}{90}\)\(\frac{1}{126}\)
=1/2.3+1/3.6+1/6.6+1/6.10+1/10.9+1/9.14
=1/2-1/3+1/3-1/6+1/6-1/6+1/6-1/10+1/10-1/9+1/9-1/14
=1/2-1/14
=6/14=3/7
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\(\frac{1}{6}+\frac{1}{18}+\frac{1}{36}+\frac{1}{60}+\frac{1}{90}+\frac{1}{126}\)
\(=\frac{1}{2\cdot3}+\frac{1}{3\cdot6}+\frac{1}{6\cdot6}+\frac{1}{6\cdot10}+\frac{1}{10\cdot9}+\frac{1}{9\cdot14}\)
\(=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{6}+\frac{1}{6}-\frac{1}{6}+\frac{1}{6}-\frac{1}{10}+\frac{1}{10}-\frac{1}{9}+\frac{1}{9}-\frac{1}{14}\)
\(=\frac{1}{2}-\frac{1}{14}\)
\(=\frac{3}{7}\)
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Tìm x thuộc Z, biết: \(1+\frac{-1}{60}+\frac{19}{120}
tìm x thuộc z biết 1 +\(\frac{1}{60}\)+ \(\frac{19}{120}< \frac{x}{36}+\frac{-1}{60}< \frac{58}{90}+\frac{59}{72}+\frac{-1}{60}\)
Tim x biet
\(1+\frac{-1}{60}+\frac{19}{120}< \frac{x}{36}< \frac{58}{90}+\frac{59}{72}+\frac{-1}{60}\)
\(1+\frac{-1}{60}+\frac{19}{120}< \frac{x}{36}< \frac{58}{90}+\frac{59}{72}+\frac{-1}{60}\)
=> \(\frac{137}{120}< \frac{x}{36}< \frac{521}{360}\)
=> \(\frac{411}{360}< \frac{10x}{360}< \frac{521}{360}\)
=> 411 < 10x < 521
=> x \(\in\){ 42,43,44,...,52}
Tính nhanh:
a)\(\frac{5}{30}+\frac{15}{90}+\frac{25}{150}+\frac{35}{210}+\frac{45}{270}\)
b)\(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{56}\)
c)\(\frac{1}{15}+\frac{4}{30}+\frac{2}{45}+\frac{16}{60}+\frac{25}{75}+\frac{36}{90}+\frac{49}{105}+\frac{64}{120}+\frac{81}{135}\)
a) 5/30+15/90+25/150+35/210+45/270
=1/6+1/6+1/6+1/6+1/6
=1/6 x 5
=5/6
b) 1/2+1/6+1/12+1/20+....+1/56
=1/1x2+1/2x3+1/3x4+1/4x5+.....1/7x8
=1/1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+.......-1/7+1/7-1/8
=1/1-1/8
=7/8
c) mình chịu
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chịu,khó quá,nhất là câu c ý
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Xem thêm câu trả lời
tìm \(x\in Z\)
\(1+\frac{-1}{60}+\frac{19}{120}<\frac{x}{36}+\frac{-1}{60}<\frac{58}{90}+\frac{59}{72}+\frac{-1}{60}\)
Tính tổng: \(S=\frac{1}{3}+\frac{1}{12}+\frac{1}{30}+\frac{1}{60}+\frac{1}{105}+\frac{1}{168}+\frac{1}{224}+\frac{1}{360}+\frac{1}{495}\)
Tính giá trị biểu thức
\(\frac{10-\frac{1}{9}-\frac{2}{10}-\frac{3}{11}-\frac{4}{12}-...-\frac{10}{18}}{\frac{1}{45}+\frac{1}{50}+\frac{1}{55}+\frac{1}{60}+...+\frac{1}{90}}\)
A=\(\frac{10-\frac{1}{9}-\frac{2}{10}-\frac{3}{11}-...-\frac{10}{18}}{\frac{1}{45}+\frac{1}{50}+\frac{1}{55}+...+\frac{1}{90}}\)