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Bài 3:
a) Ta có: \(1.25\cdot\left(-3\frac{3}{8}\right)\)
\(=\frac{5}{4}\cdot\frac{-27}{8}\)
\(=\frac{-135}{32}\)
b) Ta có: \(\frac{-9}{34}\cdot\frac{17}{4}\)
\(=\frac{-9}{4}\cdot\frac{17}{34}\)
\(=-\frac{9}{4}\cdot\frac{1}{2}\)
\(=-\frac{9}{8}\)
c) Ta có: \(-\frac{20}{41}\cdot\frac{-4}{5}\)
\(=\frac{20}{41}\cdot\frac{4}{5}\)
\(=\frac{16}{41}\)
d) Ta có: \(\frac{-6}{7}\cdot\frac{21}{2}\)
\(=-\frac{6}{2}\cdot\frac{21}{7}\)
\(=-3\cdot3=-9\)
Bài 4:
a) Ta có: \(-\frac{5}{2}\cdot\frac{3}{4}\)
\(=-\frac{5\cdot3}{2\cdot4}=\frac{-15}{8}\)
b) Ta có: \(4\frac{1}{5}:\left(-2\frac{4}{5}\right)\)
\(=-\frac{21}{5}:\frac{14}{5}\)
\(=-\frac{21}{5}\cdot\frac{5}{14}\)
\(=-\frac{21}{14}=-\frac{3}{2}\)
c) Ta có: \(1.8:\left(-\frac{3}{4}\right)\)
\(=\frac{9}{5}:\frac{-3}{4}\)
\(=\frac{9}{5}\cdot\frac{4}{-3}\)
\(=-\frac{12}{5}\)
d) Ta có: \(\frac{17}{15}:\frac{4}{3}\)
\(=\frac{17}{15}\cdot\frac{3}{4}\)
\(=\frac{17}{20}\)
\(A=\frac{15}{34}+\frac{7}{21}+\frac{9}{34}-1\frac{15}{17}+\frac{2}{3}=\frac{15}{34}+\frac{7}{21}+\frac{9}{34}-\frac{64}{34}+\frac{14}{21}=\left(\frac{15}{34}+\frac{9}{34}-\frac{64}{34}\right)+\left(\frac{7}{21}+\frac{14}{21}\right)=\frac{30}{34}+\frac{21}{21}=\frac{15}{17}+1=\frac{32}{17}\)
\(=\frac{16}{5}.\frac{15}{16}-\left(\frac{3}{4}+\frac{2}{7}\right):\left(\frac{-29}{28}\right)\)
\(=3-\left(\frac{21}{28}+\frac{8}{28}\right):\left(\frac{-29}{28}\right)\)
\(=3-\left(\frac{29}{28}\right).\left(\frac{-28}{29}\right)\)
\(=3-\left(-1\right)\)
\(=4\)
b) \(=\left(\frac{1}{4}+\frac{25}{2}-\frac{5}{16}\right):\left(12-\frac{7}{12}:\left(\frac{3}{8}-\frac{1}{12}\right)\right)\)
\(=\left(\frac{4}{16}+\frac{200}{16}-\frac{5}{16}\right):\left(12-\frac{7}{12}:\left(\frac{3.3}{2.3.4}-\frac{2}{2.3.4}\right)\right)\)
\(=\left(\frac{199}{16}\right):\left(12-\frac{7}{12}:\left(\frac{9}{24}-\frac{2}{24}\right)\right)\)
\(=\frac{199}{16}:\left(12-\frac{7}{12}.\frac{24}{7}\right)\)
\(=\frac{199}{16}:\left(12-2\right)\)
\(=\frac{199}{16}:10\)
\(=\frac{199}{160}\)
c) \(\left(\frac{-3}{5}+\frac{5}{11}\right):\frac{-3}{7}+\left(\frac{-2}{5}+\frac{6}{5}\right):\frac{-3}{7}\)
\(\left(\frac{-33}{55}+\frac{25}{55}\right):\frac{-3}{7}+\left(\frac{4}{5}\right):\frac{-3}{7}\)
\(\left(\frac{-8}{55}\right).\frac{-7}{3}+\frac{4}{5}.\frac{-7}{3}\)
\(\frac{-7}{3}\left(\frac{-8}{55}+\frac{4}{5}\right)\)
\(\frac{-7}{3}.\frac{36}{55}=\frac{-84}{55}\)
\(3\frac{1}{2}-\frac{1}{2}.\left(-4,25-\frac{3}{4}\right)^2:\frac{5}{4}\)
\(=\frac{7}{2}-\frac{1}{2}.\left(-4,25-0,75\right)^2:\frac{5}{4}\)
\(=\frac{7}{2}-\frac{1}{2}.\left(-5\right)^2:\frac{5}{4}\)
\(=\frac{7}{2}-\frac{1}{2}.5.\frac{4}{5}\)
\(=\frac{7}{2}-2\)
\(=\frac{7}{2}-\frac{4}{2}\)
\(=\frac{3}{2}\)
\(\frac{3}{7}.1\frac{1}{2}+\frac{3}{7}.0,5-\frac{3}{7}.9\)
\(=\frac{3}{7}.\left(\frac{3}{2}+\frac{1}{2}-9\right)\)
\(=\frac{3}{7}.\left(2-9\right)\)
\(=\frac{3}{7}.\left(-7\right)\)
\(=-3\)
\(\frac{125^{2016}.8^{2017}}{50^{2017}.20^{2018}}=\frac{\left(5^3\right)^{2016}.\left(2^3\right)^{2017}}{\left(5^2\right)^{2017}.2^{2017}.\left(2^2\right)^{2018}.5^{2018}}=\frac{\left(5^3\right)^{2016}.\left(2^3\right)^{2017}}{\left(5^3\right)^{2017}.\left(2^3\right)^{2017}.2.5}=\frac{1}{5^4.2}=\frac{1}{1250}\)( tính nhẩm, ko chắc đúng )
1
a) \(3\frac{1}{2}-\frac{1}{2}\cdot\left(-4,25-\frac{3}{4}\right)^2\) : \(\frac{5}{4}\)
= \(3\cdot25:\frac{5}{4}\)
= \(3\cdot\left(25:\frac{5}{4}\right)\)
=\(3\cdot20\)
=60
b)=\(\frac{3}{7}\cdot\left(1\frac{1}{2}+0,5-9\right)\)
=\(\frac{3}{7}\cdot\left(-7\right)\)
=\(-3\)
c) =
=30 nhan
= 34 - { 20 - [ 4/3 - 2.19/3] - 26} + 4/3
= 34 - {20 +34/3 - 26} + 4/3
= 34 - 16/3 + 4/3
= 30