Question

[Nguyễn Xuân Mai]

 

Answer 1

[Nguyễn Lê Phước Thịnh]

bài 2:

a: \(\dfrac{1}{9}-0,3\cdot\dfrac{5}{9}+\dfrac{1}{3}\)

\(=\dfrac{1}{9}-\dfrac{3}{10}\cdot\dfrac{5}{9}+\dfrac{1}{3}\)

\(=\dfrac{1}{9}-\dfrac{1}{6}+\dfrac{1}{3}=\dfrac{2}{18}-\dfrac{3}{18}+\dfrac{6}{18}=\dfrac{5}{18}\)

b: \(\left(-\dfrac{2}{3}\right)^2+\dfrac{1}{6}-\left(-0,5\right)^3\)

\(=\dfrac{4}{9}+\dfrac{1}{6}-\left(-\dfrac{1}{2}\right)^3\)

\(=\dfrac{8}{18}+\dfrac{3}{18}-\dfrac{-1}{8}=\dfrac{11}{18}+\dfrac{1}{8}=\dfrac{44}{72}+\dfrac{9}{72}=\dfrac{53}{72}\)

c: \(0,3-\dfrac{8}{3}:\dfrac{4}{3}\cdot\dfrac{1}{5}+1\)

\(=1,3-\dfrac{8}{3}\cdot\dfrac{3}{4}\cdot\dfrac{1}{5}=1,3-\dfrac{2}{5}=1,3-0,4=0,9=\dfrac{9}{10}\)

d: \(-\dfrac{2}{3}-4\cdot\left(\dfrac{1}{2}+\dfrac{3}{4}\right)^2\)

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

\(=-\dfrac{2}{3}-4\cdot\dfrac{25}{16}=-\dfrac{2}{3}-\dfrac{25}{4}\)

\(=-\dfrac{8}{12}-\dfrac{75}{12}=-\dfrac{83}{12}\)

e: \(2\cdot\left(-1\right)^6+\left(\dfrac{3}{4}\right)^2-\dfrac{3}{8}\)

\(=2\cdot1+\dfrac{9}{16}-\dfrac{3}{8}\)

\(=2+\dfrac{9}{16}-\dfrac{6}{16}=2+\dfrac{3}{16}=\dfrac{35}{16}\)

f: \(\left[\left(\dfrac{3}{5}-\dfrac{1}{3}\right)\cdot6+\dfrac{-1}{3}\right]\cdot5\)

\(=\left[\dfrac{9-5}{15}\cdot6+\dfrac{-1}{3}\right]\cdot5\)

\(=\left(\dfrac{4}{15}\cdot6-\dfrac{1}{3}\right)\cdot5=\dfrac{19}{15}\cdot5=\dfrac{19}{3}\)

g: \(\dfrac{3}{4}:\left(\dfrac{2}{3}-\dfrac{5}{9}\right)+\dfrac{9}{4}=\dfrac{3}{4}:\dfrac{6-5}{9}+\dfrac{9}{4}\)

\(=\dfrac{3}{4}\cdot9+\dfrac{9}{4}=\dfrac{27}{4}+\dfrac{9}{4}=\dfrac{36}{4}=9\)

h: \(0,8:\left\{0,2-8\cdot\left[\dfrac{7}{48}+\left(\dfrac{5}{24}-\dfrac{5}{16}\right)\right]\right\}\)

\(=0,8:\left\{0.2-8\cdot\left[\dfrac{7}{48}+\dfrac{10}{48}-\dfrac{15}{48}\right]\right\}\)

\(=0,8:\left\{0.2-8\cdot\dfrac{2}{48}\right\}\)

\(=0,8:\left\{0.2-\dfrac{1}{3}\right\}=0,8:\left\{\dfrac{1}{5}-\dfrac{1}{3}\right\}=0,8:\dfrac{-2}{15}=0,8\cdot\dfrac{15}{-2}=\dfrac{12}{-2}=-6\)

Bài 1:

a: \(x+\dfrac{-2}{5}=-\dfrac{1}{3}\)

=>\(x=-\dfrac{1}{3}+\dfrac{2}{5}=-\dfrac{5}{15}+\dfrac{6}{15}=\dfrac{1}{15}\)

b: \(0,5-x=-\dfrac{5}{14}\)

=>\(\dfrac{1}{2}-x=-\dfrac{5}{14}\)

=>\(x=\dfrac{1}{2}-\left(-\dfrac{5}{14}\right)=\dfrac{1}{2}+\dfrac{5}{14}=\dfrac{7}{14}+\dfrac{5}{14}=\dfrac{12}{14}=\dfrac{6}{7}\)

c: \(3\dfrac{1}{5}-x=1,6+\dfrac{7}{10}\)

=>\(3,2-x=1,6+0,7=2,3\)

=>x=3,2-2,3=0,9

d: \(\dfrac{11}{12}-\left(x+\dfrac{2}{5}\right)=\dfrac{2}{3}\)

=>\(x+\dfrac{2}{5}=\dfrac{11}{12}-\dfrac{2}{3}=\dfrac{11}{12}-\dfrac{8}{12}=\dfrac{3}{12}=\dfrac{1}{4}\)

=>\(x=\dfrac{1}{4}-\dfrac{2}{5}=\dfrac{5}{20}-\dfrac{8}{20}=-\dfrac{3}{20}\)

e: \(\dfrac{3}{4}+\dfrac{1}{4}:x=\dfrac{2}{5}\)

=>\(\dfrac{1}{4}:x=\dfrac{2}{5}-\dfrac{3}{4}=\dfrac{8}{20}-\dfrac{15}{20}=-\dfrac{7}{20}\)

=>\(x=-\dfrac{1}{4}:\dfrac{7}{20}=-\dfrac{1}{4}\cdot\dfrac{20}{7}=\dfrac{-5}{7}\)

f: \(\dfrac{3}{4}x-\dfrac{1}{2}=\dfrac{3}{7}\)

=>\(\dfrac{3}{4}x=\dfrac{1}{2}+\dfrac{3}{7}=\dfrac{7}{14}+\dfrac{6}{14}=\dfrac{13}{14}\)

=>\(x=\dfrac{13}{14}:\dfrac{3}{4}=\dfrac{13}{14}\cdot\dfrac{4}{3}=\dfrac{52}{42}=\dfrac{26}{21}\)

Answer 2

[Nguyễn Xuân Mai]

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