a, \(\frac{-1}{24}\)- [ \(\frac{1}{4}\)-( \(\frac{1}{2}\)- \(\frac{7}{8}\))]
b, [\(\frac{5}{7}\)-\(\frac{7}{5}\)] - [ \(\frac{1}{2}\)-(-\(\frac{2}{7}\)-\(\frac{1}{10}\))
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a) 20,7 + 1,47 : 7 - 0,23 . 5
= 20,7 + 0,21 – 1,15
= 20,91 – 1,15
= 19,76
Ở trên vietjack có đó bn =)
a, 20,7 + 1,47 : 7 - 0,23 . 5
=\(\frac{207}{10}+\frac{147}{100}:7-\frac{23}{100}.5\)
= \(\frac{207}{10}+\frac{21}{100}-\frac{23}{20}\)
= \(\frac{2091}{100}+\frac{-23}{20}\)
= \(\frac{494}{25}\)
Ta có :
\(\frac{\frac{2}{5}-\frac{2}{9}+\frac{2}{11}}{\frac{7}{5}-\frac{7}{9}+\frac{7}{11}}:\frac{\frac{1}{3}-\frac{1}{4}+\frac{1}{5}}{\frac{7}{6}-\frac{7}{8}+\frac{7}{10}}\)
\(=\)\(\frac{2\left(\frac{1}{5}-\frac{1}{9}+\frac{1}{11}\right)}{7\left(\frac{1}{5}-\frac{1}{9}+\frac{1}{11}\right)}:\frac{\frac{1}{3}-\frac{1}{4}+\frac{1}{5}}{\frac{7}{2}\left(\frac{1}{3}-\frac{1}{4}+\frac{1}{5}\right)}\)
\(=\)\(\frac{2}{7}:\frac{2}{7}\)
\(=\)\(\frac{2}{7}.\frac{7}{2}\)
\(=\)\(1\)
Chúc bạn học tốt ~
\(=\frac{2-2+2}{7-7+7}:\frac{\frac{2}{6}-\frac{2}{8}+\frac{2}{10}}{\frac{7}{6}-\frac{7}{8}+\frac{7}{10}}\)
\(=\frac{2}{7}:\frac{2-2+2}{7-7+7}\)
\(=\frac{2}{7}:\frac{2}{7}\)
\(=\frac{2}{7}.\frac{7}{2}\)
\(=\frac{2.7}{7.2}\)
\(=\frac{1.1}{1.1}\)
\(=\frac{1}{1}\)
\(=1\)
a: \(=\left(-\dfrac{25}{140}+\dfrac{245}{140}+\dfrac{32}{140}\right)\cdot\dfrac{-69}{20}\)
\(=\dfrac{252}{140}\cdot\dfrac{-69}{20}\)
\(=\dfrac{9}{5}\cdot\dfrac{-69}{20}=\dfrac{-621}{100}\)
b: \(=\left(6-2-\dfrac{4}{5}\right)\cdot\dfrac{25}{8}-\dfrac{8}{5}\cdot4\)
\(=\dfrac{16}{5}\cdot\dfrac{25}{8}-\dfrac{32}{5}=\dfrac{18}{5}\)
c: \(=\left(\dfrac{2}{24}+\dfrac{18}{24}+\dfrac{14}{24}\right):\dfrac{-17}{8}\)
\(=\dfrac{34}{24}\cdot\dfrac{-8}{17}=\dfrac{-1}{3}\cdot2=-\dfrac{2}{3}\)
Đáp số là 1 vì cả hai phân số đều bằng 2/7 và 2/7:2/7=14/14=1.Đúng 100000000000000000000% luôn bạn ơi!
b) \(\frac{\frac{2}{3}+\frac{5}{7}+\frac{4}{21}}{\frac{5}{6}+\frac{11}{7}-\frac{7}{21}}\)
\(=\frac{\frac{29}{21}+\frac{4}{21}}{\frac{101}{42}-\frac{7}{21}}\)
\(=\frac{\frac{11}{7}}{\frac{29}{14}}\)
\(=\frac{22}{29}.\)
Chúc bạn học tốt!
a, -1/24 - [1/4 - (1/2 - 7/8)]
= -1/24 - [1/4 - 1/2 + 7/8]
= -1/24 - 1/4 + 1/2 - 7/8
= -1/24 - 6/24 + 12/14 - 21/24
= -16/24 = -2/3
Yêu cầu tính hả ?
a ) \(\frac{-1}{24}-\left[\frac{1}{4}-\left(\frac{1}{2}-\frac{7}{8}\right)\right]\)
\(=\frac{-1}{24}-\left[\frac{1}{4}-\left(-\frac{3}{8}\right)\right]\)
\(=\frac{-1}{24}-\left[\frac{1}{4}+\frac{3}{8}\right]\)
\(=\frac{-1}{24}-\frac{5}{8}\)
\(=\frac{-2}{3}\)
b ) \(\left[\frac{5}{7}-\frac{7}{5}\right]-\left[\frac{1}{2}-\left(-\frac{2}{7}-\frac{1}{10}\right)\right]\)
\(=\left[\frac{5}{7}-\frac{7}{5}\right]-\left[\frac{1}{2}-\left(-\frac{27}{10}\right)\right]\)
\(=\left[\frac{5}{7}-\frac{7}{5}\right]-\left[\frac{1}{2}+\frac{27}{10}\right]\)
\(=\frac{-24}{35}-\frac{16}{5}\)
\(=\frac{-136}{35}\)