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a: \(-\dfrac{5}{7}\cdot\dfrac{15}{23}+\dfrac{-5}{7}\cdot\dfrac{8}{23}+\dfrac{15}{7}:\dfrac{-7}{5}\)

\(=-\dfrac{5}{7}\left(\dfrac{15}{23}+\dfrac{8}{23}\right)+\dfrac{15}{7}\cdot\dfrac{-5}{7}\)

\(=-\dfrac{5}{7}\left(1+\dfrac{15}{7}\right)\)

\(=-\dfrac{5}{7}\cdot\dfrac{22}{7}=\dfrac{-110}{49}\)

b: \(\left(\dfrac{2}{9}:\dfrac{5}{3}+\dfrac{1}{3}:\dfrac{5}{3}\right)^2-\left(\dfrac{1}{3}-\dfrac{5}{8}\right)\)

\(=\left(\dfrac{2}{9}\cdot\dfrac{3}{5}+\dfrac{1}{3}\cdot\dfrac{3}{5}\right)^2-\left(\dfrac{1}{3}-\dfrac{5}{8}\right)\)

\(=\left[\dfrac{3}{5}\left(\dfrac{2}{9}+\dfrac{1}{3}\right)\right]^2-\dfrac{8-15}{24}\)

\(=\left[\dfrac{3}{5}\cdot\dfrac{2+3}{9}\right]^2-\dfrac{-7}{24}\)

\(=\left(\dfrac{3}{5}\cdot\dfrac{5}{9}\right)^2+\dfrac{7}{24}=\dfrac{1}{9}+\dfrac{7}{24}=\dfrac{8+21}{72}=\dfrac{29}{72}\)

c: \(2\left(\dfrac{1}{4}-3x\right)=\dfrac{1}{5}-4x\)

=>\(\dfrac{1}{2}-6x=\dfrac{1}{5}-4x\)

=>\(-2x=\dfrac{1}{5}-\dfrac{1}{2}=\dfrac{-3}{10}\)

=>\(x=\dfrac{3}{20}\)

18 tháng 4 2020

Ghi đầy đủ nha

6 tháng 3 2022

bn có thể ghi rõ ràng đc ko?

a: =1/8-1/8+2/5=2/5

b: =(-1/15-14/15)+(23/27+31/27)=2-1=1

c: \(=\dfrac{3}{7}\left(\dfrac{22}{21}+\dfrac{5}{21}+\dfrac{15}{21}\right)=\dfrac{3}{7}\cdot2=\dfrac{6}{7}\)

d: \(=\dfrac{-8}{9}\cdot\dfrac{3}{2}+\dfrac{1}{9}\cdot\dfrac{-3}{2}=-\dfrac{3}{2}\)

11 tháng 6

a; \(\dfrac{3}{11}\) + \(\dfrac{5}{-9}\) + \(\dfrac{4}{11}\) - \(\dfrac{4}{9}\) + \(\dfrac{3}{17}\) + \(\dfrac{15}{11}\)

= (\(\dfrac{3}{11}\) + \(\dfrac{4}{11}\) + \(\dfrac{15}{11}\)) - (\(\dfrac{5}{9}\) + \(\dfrac{4}{9}\)) + \(\dfrac{3}{17}\)

= 2 - 1 + \(\dfrac{3}{17}\)

= 1 + \(\dfrac{3}{17}\)

\(\dfrac{20}{17}\) 

11 tháng 6

c; N = \(\dfrac{\dfrac{5}{7}-\dfrac{5}{9}-\dfrac{5}{11}}{\dfrac{15}{7}+\dfrac{15}{9}+\dfrac{15}{11}}\)

   Phải là - \(\dfrac{5}{7}\) chỗ tử số mới đúng em nhé!

2: \(=\dfrac{-2}{75}+\dfrac{5}{39}=\dfrac{33}{325}\)

3: \(=\dfrac{6}{11}\left(\dfrac{4}{9}+\dfrac{5}{9}\right)=\dfrac{6}{11}\)

4: \(=\dfrac{7}{19}\left(\dfrac{5}{13}+\dfrac{8}{13}-1\right)=-2\cdot\dfrac{7}{19}=-\dfrac{14}{19}\)

5: \(=\dfrac{2}{7}\left(\dfrac{4}{23}-\dfrac{27}{23}+1\right)=0\)

6: \(=\dfrac{3}{8}\left(\dfrac{3}{7}+\dfrac{4}{7}\right)+\dfrac{11}{8}=\dfrac{3}{8}+\dfrac{11}{8}=\dfrac{14}{8}=\dfrac{7}{4}\)

2 tháng 2 2017

ai giúp minh đi cần quá gấp

a: \(=\left(15-6-\dfrac{13}{18}\right):\dfrac{298}{27}-\dfrac{17}{8}:\dfrac{51}{40}\)

\(=\dfrac{149}{18}\cdot\dfrac{27}{298}-\dfrac{5}{3}=\dfrac{3}{2}-\dfrac{5}{3}=\dfrac{9-10}{6}=\dfrac{-1}{6}\)

b: \(=\dfrac{-16}{5}\cdot\dfrac{-15}{64}+\dfrac{-22}{15}:\dfrac{11}{2}\)

\(=\dfrac{3}{4}-\dfrac{4}{15}=\dfrac{29}{60}\)

c: \(=\dfrac{-7}{9}\left(\dfrac{4}{11}+\dfrac{7}{11}\right)+5+\dfrac{7}{9}=\dfrac{-7}{9}+\dfrac{7}{9}+5=5\)

d: \(=\dfrac{1}{2}\cdot\dfrac{4}{3}\cdot10\cdot\dfrac{1}{5}\cdot\dfrac{3}{4}=1\)

e: \(=\dfrac{4}{25}+\dfrac{11}{2}\cdot\dfrac{5}{2}+\dfrac{-23}{4}=\dfrac{204}{25}\)

oppppppopopopopopopopopopop

9 tháng 5 2020

Bài 2:

a) \(\left(3x+2\right)^3=-64\)

\(\Leftrightarrow\left(3x+2\right)^3=\left(-4\right)^3\)

\(\Leftrightarrow3x+2=\left(-4\right)\)

\(\Leftrightarrow3x=-4-2\)

\(\Leftrightarrow3x=-6\)

\(\Leftrightarrow x=-2\)

b) \(2x-3=-33\)

\(\Leftrightarrow2x=-33+3\)

\(\Leftrightarrow2x=-30\)

\(\Leftrightarrow x=-15\)