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29 tháng 6 2020

c) =-5/7x3/9+4/9x3/-7

=-5/7x3/9+3/9x4/-7

=3/9x(-5/7+4/-7)

=3/9x-9/7

=-3/7

d) =58/7 - (31/9+30/7)

=58/7-31/9-30/7

=(58/7-30/7)-(31/9)

=4-31/9

=5/9

13 tháng 6 2020

(1-1/3)x(1-1/5)x(1-1/7)x(1-1/9)x(1-1/2)x(1-1/4)x(1-1/6)x(1-1/8)x(1-1/10)

=2/3x4/5x6/7x8/9x1/2x3/4x5/6x7/8x9/10

=2x4x6x8x1x3x5x7x9 /3x5x7x9x2x4x6x8x10

=1/10

30 tháng 4 2019

\(\left(\frac{3}{8}+-\frac{3}{4}+\frac{7}{12}\right):\frac{5}{6}+\frac{1}{2}\)

\(=\left(\frac{9}{24}+-\frac{18}{24}+\frac{14}{24}\right):\frac{5}{6}+\frac{1}{2}\)

\(=\frac{5}{24}:\frac{5}{6}+\frac{1}{2}\)

\(=\frac{5}{24}.\frac{6}{5}+\frac{1}{2}\)

\(=\frac{1}{4}+\frac{1}{2}\)

\(=\frac{1}{4}+\frac{2}{4}\)

\(=\frac{3}{4}\)

30 tháng 4 2019

\(\frac{1}{2}+\frac{3}{4}-\left(\frac{3}{4}-\frac{4}{5}\right)\)

\(=\frac{1}{2}+\frac{3}{4}-\left(\frac{15}{20}-\frac{16}{20}\right)\)

\(=\frac{1}{2}+\frac{3}{4}-\frac{-1}{20}\)

\(=\frac{10}{20}+\frac{15}{20}-\frac{-1}{20}\)

\(=\frac{25}{20}-\frac{-1}{20}\)

\(=\frac{26}{20}\)

\(=\frac{13}{10}\)

13 tháng 6 2020

\(b,\left(\frac{1}{2}+1\right)\left(\frac{1}{3}+1\right)\left(\frac{1}{4}+1\right)...\left(\frac{1}{99}+1\right)\)

\(=\frac{3}{2}\cdot\frac{4}{3}\cdot\frac{5}{4}\cdot...\cdot\frac{100}{99}\)

\(=\frac{100}{2}\)

\(=50\)

19 tháng 4 2019

a) \(3^4.\left(-4\right)^2=3^4.4^2=3^4.2^4=\left(3.2\right)^4=6^4\)

b) \(=1\frac{3}{5}+\left(6+\frac{5}{11}-4-\frac{5}{11}\right).\frac{1}{5}=1+\frac{3}{5}+2.\frac{1}{5}=2\)

c)\(=4.\left(0,75-0,25\right)=4.0,5=2\)

d) \(=\frac{\frac{1}{3}+\frac{3}{4}+\frac{3}{2}}{\frac{1.4}{3.4}+\frac{3.3}{4.3}+\frac{3.6}{2.6}}=\frac{\frac{1}{3}+\frac{3}{4}+\frac{3}{2}}{\frac{1}{3}+\frac{3}{4}+\frac{3}{2}}=1\)

26 tháng 7 2019

\(\left(\frac{1}{99}+\frac{12}{999}+\frac{123}{999}\right)\left(\frac{1}{2}-\frac{1}{3}-\frac{1}{6}\right)\)

\(=\left(\frac{1}{99}+\frac{12}{999}+\frac{123}{999}\right).0\)

\(=0\)

26 tháng 7 2019

\(\left(\frac{1}{99}+\frac{12}{999}+\frac{123}{9999}\right)\left(\frac{1}{2}-\frac{1}{3}-\frac{1}{6}\right)\)=\(\left(\frac{1}{99}+\frac{12}{999}+\frac{123}{9999}\right).0=0\)