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19 tháng 3 2020

a, \(139\frac{5}{7}:\frac{2}{3}−138\frac{2}{7}:\sqrt{\frac{4}{9}} \)

= \(139\frac{5}{7}:\frac{2}{3}−138\frac{2}{7}:\frac{2}{3}\)

= \((139\frac{5}{7}−138\frac{2}{7}):\frac{2}{3}\)

= \(1\frac{3}{7}:\frac{2}{3}\)

= \(2\frac{1}{7}\)

b, \((\frac{-5}{11}:\frac{13}{18}-\frac{5}{11}:\frac{13}{5})+\frac{-1}{33} \)

= \((\frac{5}{11}.\frac{-18}{13}-\frac{5}{11}.\frac{5}{13})+\frac{-1}{33}\)

= \([\frac{5}{11}.(\frac{-18}{13}-\frac{5}{13})]+\frac{-1}{33}\)

= \((\frac{5}{11}.\frac{-23}{13})+\frac{-1}{33}\)

= \(\frac{-155}{143}+\frac{-1}{33}\)

= \(\frac{-358}{429} \)

c, \(∣97\frac{2}{3}-125\frac{3}{5}∣+97\frac{2}{3}-125\frac{3}{5} \)

= \(∣\frac{-419}{15}∣+97\frac{2}{3}-125\frac{3}{5}\)

= \(\frac{419}{15}+97\frac{2}{3}-125\frac{3}{5}\)

= \(0\)

Tick cho mình nha!!!

Chúc bạn học tốt.

\(=\)\(\left(\frac{1}{125}-\frac{1}{1^3}\right)\)  \(.\) \(\left(\frac{1}{125}-\frac{1}{2^3}\right)\) \(.\) \(\left(\frac{1}{125}-\frac{1}{3^3}\right)\) \(.\)  \(\left(\frac{1}{125}-\frac{1}{5^3}\right)\)\(...\) \(\left(\frac{1}{125}-\frac{1}{25^3}\right)\)

\(=\) \(\left(\frac{1}{125}-\frac{1}{1^3}\right)\) \(.\) \(\left(\frac{1}{125}-\frac{1}{2^3}\right)\) \(.\) \(\left(\frac{1}{125}-\frac{1}{3^3}\right)\) \(.\) \(0\) \(....\) \(\left(\frac{1}{125}-\frac{1}{25^3}\right)\)

\(=\) \(0\)

Ta có: \(\left|97\dfrac{2}{3}-125\dfrac{3}{5}\right|+97\dfrac{2}{5}-125\dfrac{1}{3}\)

\(=\left|97+\dfrac{2}{3}-125-\dfrac{3}{5}\right|+97+\dfrac{2}{5}-125-\dfrac{1}{3}\)

\(=\left|-28+\dfrac{1}{15}\right|-28+\dfrac{1}{15}\)

\(=\left|\dfrac{1}{15}-28\right|-28+\dfrac{1}{15}\)

\(=28-\dfrac{1}{15}-28+\dfrac{1}{15}\)

\(=0\)

\(\left(\frac{1}{125}-\frac{1}{1^3}\right)\left(\frac{1}{125}-\frac{1}{2^3}\right)...\left(\frac{1}{125}-\frac{1}{25^3}\right)\)

\(=\left(\frac{1}{125}-\frac{1}{1^3}\right)\left(\frac{1}{125}-\frac{1}{2^3}\right)...\left(\frac{1}{125}-\frac{1}{5^3}\right)...\left(\frac{1}{125}-\frac{1}{25^3}\right)\)

\(=\left(\frac{1}{125}-\frac{1}{1^3}\right)\left(\frac{1}{125}-\frac{1}{2^3}\right)...0...\left(\frac{1}{125}-\frac{1}{25^3}\right)\)

\(=0\)