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27 tháng 7 2020

\(\left[\left(6\frac{3}{7}-\frac{0,75x-2}{0,35}\right)\cdot2,8+1,75\right]:0,05=235\)

\(\Leftrightarrow\left(6\frac{3}{7}-\frac{0,75x-2}{0,35}\right)\cdot2,8+1,75=11,75\)

\(\Leftrightarrow\left(6\frac{3}{7}-\frac{0,75x-2}{0,35}\right)\cdot2,8=10\)

\(\Leftrightarrow\left(6\frac{3}{7}-\frac{0,75x-2}{0,35}\right)\cdot2,8=10\)

\(\Leftrightarrow6\frac{3}{7}-\frac{0,75x-2}{0,35}=\frac{25}{7}\)

\(\Leftrightarrow\frac{0,75x-2}{0,35}=\frac{20}{7}\)

\(\Leftrightarrow0,75x-2=1\)

\(\Leftrightarrow0,75x=3\)

\(\Leftrightarrow x=4\)

Vậy \(x=4\)

17 tháng 9 2016

\(\Leftrightarrow\left(\left(6\frac{3}{7}-\frac{0,75x-2}{0,35}\right).2,8+1,75\right)=0,1175\)

\(\Leftrightarrow\left(\frac{45}{7}-\frac{0,75x-2}{0,35}\right).2,8=-1,6325\)

\(\Leftrightarrow\frac{45}{7}-\frac{0,75x-2}{0,35}=\frac{-653}{1120}\)

\(\Leftrightarrow\frac{0,75x-2}{0,35}=\frac{7853}{1120}\Leftrightarrow x=5,93875\)

a: Sửa đề: \(\left[\left(6\dfrac{3}{7}-\dfrac{0,75x-2}{0,35}\right)\cdot2.8+1.75\right]\cdot0.05=2.35\)

\(\Leftrightarrow\left(\dfrac{45}{7}-\dfrac{15x-40}{7}\right)\cdot2.8+1,75=47\)

\(\Leftrightarrow\dfrac{45-15x+40}{7}\cdot2,8=45,25\)

\(\Leftrightarrow\dfrac{85-15x}{7}=\dfrac{905}{56}\)

=>8(85-15x)=905

=>680-120x=905

=>120x=-225

hay x=-15/8

b: \(\dfrac{3}{5}-\dfrac{2}{7}< \dfrac{2}{3}x+\dfrac{3}{4}< \dfrac{1}{2}+\dfrac{7}{9}\)

\(\Leftrightarrow\dfrac{11}{35}-\dfrac{3}{4}< \dfrac{2}{3}x< \dfrac{23}{18}-\dfrac{3}{4}\)

\(\Leftrightarrow-\dfrac{61}{140}< \dfrac{2}{3}x< \dfrac{19}{36}\)

\(\Leftrightarrow-\dfrac{183}{280}< x< \dfrac{19}{24}\)

28 tháng 7 2016

\(2\frac{2}{3}:\left\{\left[\left(3,72-0,02.x\right)\frac{10}{37}\right]:\frac{5}{6}+2,8\right\}-\frac{7}{15}=0,2\)

\(2\frac{2}{3}:\left\{\left[\left(3,75-0,02.x\right)\frac{10}{37}\right]:\frac{5}{6}+2,8\right\}=\frac{2}{3}\)

\(\left\{\left[\left(3,72-0,02.x\right)\frac{10}{37}\right]:\frac{5}{6}+2,8\right\}=4\)

\(\left[\left(3,72-0,02.x\right)\frac{10}{37}\right]:\frac{5}{6}=\frac{6}{5}\)

\(\left[\left(3,72-0,02.x\right)\frac{10}{37}\right]=1\)

\(\left(3,72-0,02.x\right)=\frac{37}{10}\)

\(0,02.x=0,02\)

\(x=1\)

28 tháng 7 2016

\(2\frac{2}{3}:\left\{\left[\left(3,72-0,02.x\right)\frac{10}{37}\right]:\frac{5}{6}+2,8\right\}-\frac{7}{15}=0,2\)

\(\Rightarrow\frac{8}{3}:\left\{\left[\left(\frac{93}{25}-\frac{1}{50}.x\right)\frac{10}{37}\right]:\frac{5}{6}+\frac{14}{5}\right\}-\frac{7}{15}=\frac{1}{5}\)

\(\Rightarrow\left\{\left[\frac{93}{25}-\frac{1}{50}.x\right]:\frac{5}{6}+\frac{14}{5}\right\}-\frac{7}{15}=\frac{8}{3}:\frac{1}{5}=\frac{40}{3}\)

\(\Rightarrow\left[\frac{93}{25}-\frac{1}{50}.x\right]:\frac{5}{6}+\frac{14}{5}=\frac{40}{3}+\frac{7}{15}=\frac{69}{5}\)

\(\Rightarrow\left[\frac{93}{25}-\frac{1}{50}.x\right]:\frac{5}{6}=\frac{69}{5}-\frac{14}{5}=11\)

\(\Rightarrow\frac{93}{25}-\frac{1}{50}.x=11.\frac{5}{6}=\frac{55}{6}\)

\(\Rightarrow\frac{1}{50}.x=\frac{93}{25}-\frac{55}{6}=\frac{-817}{150}\)

\(\Rightarrow x=\frac{-817}{150}:\frac{1}{50}=\frac{-817}{3}\)

Ủng hộ tớ nha m.n?