\(=\dfrac{7}{5}\cdot\dfrac{15}{49}-\left(\dfrac{4}{5}-\dfrac{2}{3}\right):\dfrac{11}{5}\)

\(=\dfrac{3}{7}-\dfrac{2}{15}\cdot\dfrac{5}{11}\)

\(=\dfrac{3}{7}-\dfrac{2}{33}=\dfrac{99-14}{33\cdot7}=\dfrac{85}{231}\)

\(1,4\cdot\dfrac{15}{49}-\left(\dfrac{4}{5}+\dfrac{2}{3}\right):2\dfrac{1}{5}\\ =\dfrac{7}{5}\cdot\dfrac{15}{49}-\dfrac{22}{15}:\dfrac{11}{5}\\ =\dfrac{3}{7}-\dfrac{22}{15}\cdot\dfrac{5}{11}=\dfrac{3}{7}-\dfrac{2}{3}=-\dfrac{5}{21}\)

1,4.15/49-(4/5+2/3): 2/1/5

= 7/5. 15/49 - 2/15: 11/5

= 3/7 - 2/33

= 85/231

a) \(\dfrac{1}{4}-\dfrac{2}{-3}+\dfrac{11}{8}\\ =\dfrac{6+16-33}{24}=-\dfrac{11}{24}\)

b) \(1,4.\dfrac{15}{49}-\left(\dfrac{4}{5}+\dfrac{2}{3}\right):2\dfrac{1}{5}\\ =\dfrac{7}{5}.\dfrac{15}{49}-\dfrac{22}{15}:\dfrac{11}{5}\\ =\dfrac{3}{7}-\dfrac{2}{3}\\ =\dfrac{9-14}{21}=-\dfrac{5}{21}\)

a, \(\dfrac{1}{4}-\dfrac{2}{-3}-\dfrac{11}{8}.\)

\(=\dfrac{1}{4}+\dfrac{2}{3}+\dfrac{-11}{8}.\)

\(=\dfrac{6}{24}+\dfrac{16}{24}+\dfrac{33}{24}.\)

\(=\dfrac{6+16+\left(-33\right)}{24}.\)

\(=\dfrac{-11}{24}.\)

b, \(1,4.\dfrac{15}{49}-\left(\dfrac{4}{5}+\dfrac{2}{3}\right):2\dfrac{1}{5}.\)

\(=\dfrac{7}{5}.\dfrac{15}{49}-\left(\dfrac{12}{15}+\dfrac{10}{15}\right):\dfrac{11}{5}.\)

\(=\dfrac{3}{7}-\dfrac{22}{15}:\dfrac{11}{5}.\)

\(=\dfrac{3}{7}-\dfrac{22}{15}.\dfrac{5}{11}.\)

\(=\dfrac{3}{7}-\dfrac{22.5}{15.11}.\)

\(=\dfrac{3}{7}-\dfrac{2.1}{3.1}.\)

\(=\dfrac{3}{7}-\dfrac{2}{3}.\)

\(=\dfrac{9}{21}-\dfrac{14}{21}.\)

\(=\dfrac{9-14}{21}=\dfrac{-5}{21}.\)

CHÚC BN HỌC TỐT!!! ^ - ^

\(A=-1,6:\left(1+\dfrac{2}{3}\right)\)

\(A=\dfrac{-16}{10}:\dfrac{5}{3}\)

\(A=\dfrac{-8}{5}.\dfrac{3}{5}\)

\(A=\dfrac{-24}{25}\)

\(B=1,4.\dfrac{15}{49}-\left(\dfrac{4}{5}+\dfrac{2}{3}\right):2\dfrac{1}{5}\)

\(B=\dfrac{14}{10}.\dfrac{15}{49}-\left(\dfrac{4}{5}+\dfrac{2}{3}\right):\dfrac{11}{5}\)

\(B=\dfrac{14}{10}.\dfrac{15}{49}-\dfrac{22}{15}:\dfrac{11}{5}\)

\(B=\dfrac{3}{7}-\dfrac{22}{15}:\dfrac{11}{5}\)

\(B=\dfrac{3}{7}-\dfrac{2}{3}\)

\(B=\dfrac{-5}{21}\)

\(A=-1,6:\left(1+\dfrac{2}{3}\right)\)
\(A=\dfrac{-8}{5}:\left(1+\dfrac{2}{3}\right)\)
\(A=\dfrac{-8}{5}:\dfrac{5}{3}\)
\(A=\dfrac{-24}{25}\)

\(B=1,4.\dfrac{15}{49}-\left(\dfrac{4}{5}+\dfrac{2}{3}\right):2\dfrac{1}{5}\)
\(B=\dfrac{7}{5}.\dfrac{15}{49}-\left(\dfrac{4}{5}+\dfrac{2}{3}\right):\dfrac{11}{5}\)
\(B=\dfrac{7}{5}.\dfrac{15}{49}-\dfrac{22}{15}:\dfrac{11}{5}\)
\(B=\dfrac{3}{7}-\dfrac{2}{3}\)
\(B=\dfrac{-5}{21}\)

\(A=-1,6:\left(1+\dfrac{2}{3}\right)\)

\(\Rightarrow A=\dfrac{-8}{5}:\left(1+\dfrac{2}{3}\right)\)

\(\Rightarrow A=\dfrac{-8}{5}:\left(\dfrac{3}{3}+\dfrac{2}{3}\right)\)

\(\Rightarrow A=\dfrac{-8}{5}:\dfrac{5}{3}\)

\(\Rightarrow A=\dfrac{-8}{5}.\dfrac{3}{5}\)

\(\Rightarrow A=\dfrac{-24}{25}\)

\(B=1,4.\dfrac{15}{49}-\left(\dfrac{4}{5}+\dfrac{2}{3}\right):2\dfrac{1}{5}\)

\(\Rightarrow B=\dfrac{7}{5}.\dfrac{15}{49}-\left(\dfrac{12}{15}+\dfrac{10}{15}\right):\dfrac{11}{5}\)

\(\Rightarrow B=\dfrac{3}{7}-\dfrac{22}{15}.\dfrac{5}{11}\)

\(\Rightarrow B=\dfrac{3}{7}-\dfrac{2}{3}\)

\(\Rightarrow B=\dfrac{9}{21}-\dfrac{14}{21}\)

\(\Rightarrow B=\dfrac{9}{21}+\left(\dfrac{-14}{21}\right)\)

\(\Rightarrow B=\dfrac{-5}{21}\)

Cái này bn lầy máy tính ra tính tí là xong thôi

a) \(2\dfrac{3}{4}.\left(-0,4\right)-1\dfrac{3}{5}.2,75+\left(-1,2\right):\dfrac{4}{11}\)

= \(2,75.\left(-0,4\right)-\left(1,6\right).\left(2,75\right)+\left(-1,2\right).\dfrac{11}{4}\)

= \(2,75.\left(-0,4\right)-\left(1,6\right).\left(2,75\right)+\left(-1,2\right).\left(2,75\right)\)

= \(2,75.\left\{\left(-0,4\right)-\left(1,6\right)+\left(-1,2\right)\right\}\)

= \(2,75.\left(-3,2\right)\)

= \(-8,8\)

b) \(1,4.\dfrac{15}{49}-\left(\dfrac{4}{5}+\dfrac{2}{3}\right):2\dfrac{1}{5}\)

= \(\dfrac{7}{5}.\dfrac{15}{49}-\left(\dfrac{4}{5}+\dfrac{2}{3}\right):\dfrac{11}{5}\)

= \(\dfrac{7}{5}.\dfrac{15}{49}-\dfrac{22}{15}.\dfrac{5}{11}\)

= \(\dfrac{3}{7}-\dfrac{2}{3}\)

= \(-\dfrac{5}{21}\)

c) \(\left(-3,2\right).\dfrac{15}{64}+\left(0,8-2\dfrac{4}{15}\right):3\dfrac{2}{3}\)

= \(-\dfrac{16}{5}.\dfrac{15}{64}+\left(\dfrac{4}{5}-2\dfrac{4}{15}\right):\dfrac{11}{3}\)

= \(-\dfrac{16}{5}.\dfrac{15}{64}+\left(-\dfrac{22}{15}\right).\dfrac{3}{11}\)

= \(\left(-\dfrac{3}{4}\right)+\left(-\dfrac{2}{5}\right)\)

= \(-\dfrac{23}{20}\)

d) \(0,02.\dfrac{-25}{2}+\dfrac{3}{8}+\left(-2\dfrac{9}{20}\right).\dfrac{2}{7}\)

= \(\dfrac{1}{50}.\dfrac{-25}{2}+\dfrac{3}{8}+\left(-\dfrac{49}{20}\right).\dfrac{2}{7}\)

=\(\left(-\dfrac{1}{4}\right)+\dfrac{3}{8}+\left(-\dfrac{7}{10}\right)\)

= \(\dfrac{1}{8}+\left(-\dfrac{7}{10}=\right)\)

= \(-\dfrac{23}{40}\)

e) \(34\%:\dfrac{51}{16}-3\dfrac{7}{9}.6,5-\left(0,4\right)^2\)

= \(\dfrac{17}{50}.\dfrac{16}{51}-\dfrac{34}{9}.\dfrac{13}{2}-\dfrac{4}{25}\)

= \(\dfrac{8}{75}-\dfrac{221}{9}-\dfrac{4}{15}\)

= \(-\dfrac{5501}{225}\)

a, \(\dfrac{-5}{12}.\dfrac{2}{7}+\dfrac{7}{12}:\dfrac{-14}{3}\)

\(=\dfrac{-5}{42}+\dfrac{7}{12}:\dfrac{-14}{3}\)

\(=\dfrac{-5}{42}+\dfrac{-1}{8}\)

\(=\dfrac{-41}{168}\)

b, \(1,4.\dfrac{15}{49}-\left(80\%+\dfrac{2}{3}\right):2\dfrac{1}{5}\)

\(=1,4.\dfrac{15}{49}-\dfrac{22}{15}:2\dfrac{1}{5}\)

\(=\dfrac{3}{7}-\dfrac{22}{15}:2\dfrac{1}{5}\)

\(=\dfrac{3}{7}-\dfrac{2}{3}\)

\(=\dfrac{-5}{21}\)

\(\dfrac{-5}{12}.\dfrac{2}{7}+\dfrac{7}{12}:\dfrac{-14}{3}=\dfrac{-5}{42}+\dfrac{-1}{8}\)

\(=\dfrac{-20}{168}+\dfrac{-8820}{168}=\dfrac{-8840}{168}=\dfrac{-1105}{21}\)

a, \(\dfrac{-5}{12}.\dfrac{2}{7}+\dfrac{7}{12}:\dfrac{-14}{3}\)

\(=\dfrac{-5}{42}+\dfrac{-1}{8}\)

\(=\dfrac{-41}{168}\)

b, \(1,4.\dfrac{15}{49}-\left(80\%+\dfrac{2}{3}\right):2\dfrac{1}{5}\)

\(=\dfrac{7}{5}.\dfrac{15}{49}-\left(\dfrac{4}{5}+\dfrac{2}{3}\right).\dfrac{5}{11}\)

\(=\dfrac{3}{7}-\dfrac{22}{15}.\dfrac{5}{11}\)

\(=\dfrac{3}{7}-\dfrac{2}{3}\)

\(=\dfrac{-5}{21}\)

Bài 1 : Rút gọn các phân số sau đến tối giản :

a) \(\dfrac{3.21}{14.15}=\dfrac{3.3.7}{2.7.3.5}=\dfrac{1.3.1}{2.1.1.5}=\dfrac{3}{10}\)

b) \(\dfrac{49+49.7}{49}=\dfrac{49\left(1+7\right)}{49}=\dfrac{49.8}{49}=\dfrac{1.8}{1}=\dfrac{8}{1}=8\)

A -\(\dfrac{24}{25}\)

B -\(\dfrac{5}{21}\)

C -\(\dfrac{24}{47}\)

D -\(\dfrac{19}{42}\)

tick cho mk