\(\frac{1}{6}\)+\(\frac{1}{18}\)+\(\frac{1}{36}\)+\(\frac{1}{60}\)+\(\frac{1}{90}\)\(\frac{1}{126}\)
Những câu hỏi liên quan
\(A=\frac{1}{18}+\frac{1}{36}+\frac{1}{60}+\frac{1}{90}+\frac{1}{126}+\frac{1}{168}\)
\(A=\frac{1}{18}+\frac{1}{36}+\frac{1}{60}+...+\frac{1}{168}\)
\(\frac{1}{3}A=\frac{1}{54}+\frac{1}{108}+...+\frac{1}{504}\)
\(\frac{1}{3}A=\frac{1}{6.9}+\frac{1}{9.12}+...+\frac{1}{21.24}\)
\(=\frac{1}{6}-\frac{1}{9}+\frac{1}{9}-\frac{1}{12}+...+\frac{1}{21}-\frac{1}{24}\)
\(=\frac{1}{6}-\frac{1}{24}\)
\(=\frac{4-1}{24}=\frac{3}{24}=\frac{1}{8}\)
=> \(A=\frac{1}{8}:\frac{1}{3}\)\(=\frac{3}{8}\)
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Tìm x thuộc Z, biết: \(1+\frac{-1}{60}+\frac{19}{120}
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 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}
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 giá trị biểu thức
\(\frac{10-\frac{1}{9}-\frac{2}{10}-\frac{3}{11}-\frac{4}{12}-...-\frac{10}{18}}{\frac{1}{45}+\frac{1}{50}+\frac{1}{55}+\frac{1}{60}+...+\frac{1}{90}}\)
TínhA= \(\frac{-1}{2}+\frac{-1}{6}+\frac{-1}{12}+\frac{-1}{20}+\frac{-1}{30}+\frac{-1}{42}+\frac{-1}{36}+\frac{-1}{72}+\frac{-1}{90}\)
Xem chi tiết
\(=-\left(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{9.10}\right)\)
\(=-\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{9}-\frac{1}{10}\right)\)
\(=-\left(1-\frac{1}{10}\right)=-\frac{9}{10}\)
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Tính :
M = \(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+...+\frac{1}{4970}\)
N = \(\frac{1}{18}+\frac{1}{54}+\frac{1}{108}+...+\frac{1}{990}\)
P = \(\frac{1}{90}-\frac{1}{72}-\frac{1}{56}-...-\frac{1}{6}-\frac{1}{2}\)
\(N=\frac{1}{3.6}+\frac{1}{6.9}+...+\frac{1}{30.33}\)
=\(\frac{1}{3}\left(\frac{1}{3}-\frac{1}{6}+\frac{1}{6}-\frac{1}{9}+...+\frac{1}{30}-\frac{1}{33}\right)\)
=\(\frac{1}{3}\left(\frac{1}{3}-\frac{1}{33}\right)=\frac{10}{33}\)
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\(M=\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+...+\frac{1}{4970}\)
\(M=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{70.71}\)
\(M=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{70}-\frac{1}{71}\)
\(M=1-\frac{1}{71}\)
\(M=\frac{70}{71}\)
\(N=\frac{1}{18}+\frac{1}{54}+\frac{1}{108}+...+\frac{1}{990}\)
\(N=\frac{1}{3.6}+\frac{1}{6.9}+\frac{1}{9.12}+...+\frac{1}{30.33}\)
\(N=\frac{1}{3}.\left(\frac{3}{3.6}+\frac{3}{6.9}+\frac{3}{9.12}+...+\frac{3}{30.33}\right)\)
\(N=\frac{1}{3}.\left(\frac{1}{3}-\frac{1}{6}+\frac{1}{6}-\frac{1}{9}+\frac{1}{9}-\frac{1}{12}+...+\frac{1}{30}-\frac{1}{33}\right)\)
\(N=\frac{1}{3}.\left(\frac{1}{3}-\frac{1}{33}\right)\)
\(N=\frac{1}{3}.\frac{10}{33}\)
\(N=\frac{10}{99}\)
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