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2, \(\frac{10}{1.2.3}+\frac{10}{2.3.4}+\frac{10}{3.4.5}+....+\frac{10}{100.101.102}\)
\(=\frac{3-1}{1.2.3}+\frac{4-2}{2.3.4}+\frac{5-3}{3.4.5}+...+\frac{102-100}{100.101.102}\)
\(=\frac{10}{2}.\left(\frac{1}{1.2}-\frac{1}{2.3}+\frac{1}{2.3}-\frac{1}{3.4}+\frac{1}{3.4}-\frac{1}{4.5}+...+\frac{1}{100.101}-\frac{1}{101.102}\right)\)
\(=\frac{10}{2}.\left(\frac{1}{1.2}-\frac{1}{101.102}\right)\)
\(=\frac{10}{2}.\frac{2575}{5151}\)
\(=2,499514657\)
a. \(\frac{-3}{2}-2x+\frac{3}{4}=-22\)2
=> \(-2x=-22+\frac{3}{2}-\frac{3}{4}\)
=> \(-2x=\frac{-85}{4}\)
=> \(x=\frac{-85}{4}:\left(-2\right)\)
=> \(x=\frac{85}{8}\)
b. \(\left(\frac{-2}{3}x-\frac{3}{5}\right).\left(\frac{3}{-2}-\frac{10}{3}\right)=\frac{2}{5}\)
=> \(\left(\frac{-2}{3}x-\frac{3}{5}\right).\frac{-29}{6}=\frac{2}{5}\)
=> \(\frac{-2}{3}x-\frac{3}{5}=\frac{2}{5}:\left(\frac{-29}{6}\right)\)
=> \(\frac{-2}{3}x-\frac{3}{5}=\frac{-12}{145}\)
=> \(\frac{-2}{3}x=\frac{-12}{145}+\frac{3}{5}\)
=> \(\frac{-2}{3}x=\frac{15}{29}\)
=> x = \(\frac{15}{29}:\frac{-2}{3}\)
=> x = \(\frac{-45}{58}\)
a, \(\frac{1}{2}\cdot\frac{2}{3}\cdot\frac{3}{4}\cdot\frac{4}{5}\cdot\frac{5}{6}=\frac{1\cdot2\cdot3\cdot4\cdot5}{2\cdot3\cdot4\cdot5\cdot6}=\frac{1}{6}\)
b, 10,3 x 37,5 - 37,5 x 10,2
= 37,5 x ( 10,3 - 10,2 )
= 37,5 x 0,1
= 3,75
a) \(\frac{1}{2}\times\frac{2}{3}\times\frac{3}{4}\times\frac{4}{5}\times\frac{5}{6}\)
\(=\frac{1\times2\times3\times4\times5}{2\times3\times4\times5\times6}\)
\(=\frac{1}{6}\)
b) 10,3 x 37,5 - 37,5 x 10,2
= 37,5 x ( 10,3 - 10,2 )
= 37,5 x 0,1
= 3,75
Phân số lớn nhất :\(\frac{9}{10}\)
Phân số bé nhất :\(\frac{1}{2}\)
\(\left(\frac{2}{5}:X\right)x\frac{1}{3}=\frac{4}{5}\)
\(\left(\frac{2}{5}:X\right)=\frac{4}{5}:\frac{1}{3}\)
\(\frac{2}{5}:X=\frac{12}{5}\)
\(X=\frac{2}{5}:\frac{12}{5}\)
\(X=\frac{1}{6}\)
\(2x\left(\frac{4}{5}:X\right)=\frac{3}{7}\)
\(\frac{4}{5}:X=\frac{3}{7}:2\)
\(\frac{4}{5}:X=\frac{3}{14}\)
\(X=\frac{4}{5}:\frac{3}{14}\)
\(X=\frac{56}{15}\)
\(\left[\frac{2}{5}:x\right]\times\frac{1}{3}=\frac{4}{5}\)
\(\Leftrightarrow\frac{2}{5}:x=\frac{12}{5}\)
\(\Leftrightarrow x=\frac{2}{5}:\frac{12}{5}=\frac{2}{5}\times\frac{5}{12}=\frac{1}{1}\times\frac{1}{6}=\frac{1}{6}\)
\(2\times\left[\frac{4}{5}:x\right]=\frac{3}{7}\)
\(\Leftrightarrow\frac{4}{5}:x=\frac{3}{7}:2\)
\(\Leftrightarrow\frac{4}{5}:x=\frac{3}{7}\times\frac{1}{2}\)
\(\Leftrightarrow\frac{4}{5}:x=\frac{3}{14}\)
\(\Leftrightarrow x=\frac{4}{5}:\frac{3}{14}=\frac{4}{5}\times\frac{14}{3}=\frac{56}{15}\)
trả lời
đúng
vì x là 1
chúc bn học tốt
\(2\frac{3}{4}< 2.\frac{3}{4}\left(s\right)\)
\(2\frac{3}{4}=2\cdot\frac{3}{4}\left(s\right)\)
\(2\frac{3}{4}>2.\frac{3}{4}\left(\text{đ}\right)\)