Question

tìm số x , biết :

a) \(\frac{2}{3}x-\frac{3}{2}x=\frac{5}{12}\)

b) \(\frac{2}{5}+\frac{3}{5}.\left(3x-3,7\right)=\frac{-53}{10}\)

c) \(\frac{7}{9}:\left(2+\frac{3}{4}x\right)+\frac{5}{9}=\frac{23}{27}\)

d) \(\frac{-2}{3}.x+\frac{1}{5}=\frac{3}{10}\)

e) \(\left|x\right|-\frac{3}{4}=\frac{5}{3}\)

f) \(\left|2x-\frac{1}{3}\right|+\frac{5}{6}=1\)

Answer 1

a.

\(\frac{2}{3}x-\frac{3}{2}x=\frac{5}{12}\)

\(\left(\frac{2}{3}-\frac{3}{2}\right)\times x=\frac{5}{2}\)

\(\left(\frac{4-9}{6}\right)\times x=\frac{5}{2}\)

\(-\frac{5}{6}\times x=\frac{5}{2}\)

\(x=\frac{5}{2}\div\left(-\frac{5}{6}\right)\)

\(x=\frac{5}{2}\times\left(-\frac{6}{5}\right)\)

\(x=-3\)

b.

\(\frac{2}{5}+\frac{3}{5}\times\left(3x-3,7\right)=-\frac{53}{10}\)

\(\frac{3}{5}\times\left(3x-3,7\right)=-\frac{53}{10}-\frac{2}{5}\)

\(\frac{3}{5}\times\left(3x-3,7\right)=\frac{-53-4}{10}\)

\(\frac{3}{5}\times\left(3x-3,7\right)=-\frac{57}{10}\)

\(3x-3,7=-\frac{57}{10}\div\frac{3}{5}\)

\(3x-3,7=-\frac{57}{10}\times\frac{5}{3}\)

\(3x-\frac{37}{10}=-\frac{19}{2}\)

\(3x=-\frac{19}{2}+\frac{37}{10}\)

\(3x=\frac{-95+37}{10}\)

\(3x=-\frac{58}{10}\)

\(3x=-\frac{29}{5}\)

\(x=-\frac{29}{5}\div3\)

\(x=-\frac{29}{5}\times\frac{1}{3}\)

\(x=-\frac{29}{15}\)

c.

\(\frac{7}{9}\div\left(2+\frac{3}{4}x\right)+\frac{5}{9}=\frac{23}{27}\)

\(\frac{7}{9}\div\left(2+\frac{3}{4}x\right)=\frac{23}{27}-\frac{5}{9}\)

\(\frac{7}{9}\div\left(2+\frac{3}{4}x\right)=\frac{23-15}{27}\)

\(\frac{7}{9}\div\left(2+\frac{3}{4}x\right)=\frac{8}{27}\)

\(2+\frac{3}{4}x=\frac{7}{9}\div\frac{8}{27}\)

\(2+\frac{3}{4}x=\frac{7}{9}\times\frac{27}{8}\)

\(2+\frac{3}{4}x=\frac{21}{8}\)

\(\frac{3}{4}x=\frac{21}{8}-2\)

\(\frac{3}{4}x=\frac{21-16}{8}\)

\(\frac{3}{4}x=\frac{5}{8}\)

\(x=\frac{5}{8}\div\frac{3}{4}\)

\(x=\frac{5}{8}\times\frac{4}{3}\)

\(x=\frac{5}{6}\)

d.

\(-\frac{2}{3}\times x+\frac{1}{5}=\frac{3}{10}\)

\(-\frac{2}{3}\times x=\frac{3}{10}-\frac{1}{5}\)

\(-\frac{2}{3}\times x=\frac{3-2}{10}\)

\(-\frac{2}{3}\times x=\frac{1}{10}\)

\(x=\frac{1}{10}\div\left(-\frac{2}{3}\right)\)

\(x=\frac{1}{10}\times\left(-\frac{3}{2}\right)\)

\(x=-\frac{3}{20}\)

e.

\(\left|x\right|-\frac{3}{4}=\frac{5}{3}\)

\(\left|x\right|=\frac{5}{3}+\frac{3}{4}\)

\(\left|x\right|=\frac{20+9}{12}\)

\(\left|x\right|=\frac{29}{12}\)

\(x=\pm\frac{29}{12}\)

Vậy \(x=\frac{29}{12}\) hoặc \(x=-\frac{29}{12}\)

f.

\(\left|2x-\frac{1}{3}\right|+\frac{5}{6}=1\)

\(\left|2x-\frac{1}{3}\right|=1-\frac{5}{6}\)

\(\left|2x-\frac{1}{3}\right|=\frac{6-5}{6}\)

\(\left|2x-\frac{1}{3}\right|=\frac{1}{6}\)

\(2x-\frac{1}{3}=\pm\frac{1}{6}\)

\(2x-\frac{1}{3}=\frac{1}{6}\)

                \(2x=\frac{1}{6}+\frac{1}{3}\)

                \(2x=\frac{1+2}{6}\)

                \(2x=\frac{3}{6}\)

                \(2x=\frac{1}{2}\)

                  \(x=\frac{1}{2}\div2\)

                  \(x=\frac{1}{2}\times\frac{1}{2}\)

                  \(x=\frac{1}{4}\)

\(2x-\frac{1}{3}=-\frac{1}{6}\)

                \(2x=-\frac{1}{6}+\frac{1}{3}\)

                \(2x=\frac{-1+2}{6}\)

                \(2x=\frac{1}{6}\)

                 \(x=\frac{1}{6}\div2\)

                 \(x=\frac{1}{6}\times\frac{1}{2}\)

                 \(x=\frac{1}{12}\)

Vậy x = 1/4 hoặc x = 1/12.

Chúc bạn học tốt

Answer 2

Sorry nha, mik chép lộn đềLàm lại câu a nha

a.

\(\frac{2}{3}x-\frac{3}{2}x=\frac{5}{12}\)

\(\left(\frac{2}{3}-\frac{3}{2}\right)\times x=\frac{5}{12}\)

\(\left(\frac{4-9}{6}\right)\times x=\frac{5}{12}\)

\(-\frac{5}{6}\times x=\frac{5}{12}\)

\(x=\frac{5}{12}\div\left(-\frac{5}{6}\right)\)

\(x=\frac{5}{12}\times\left(-\frac{6}{5}\right)\)

\(x=-\frac{1}{2}\)

Chúc bạn học tốt

Answer 3

\(a,\frac{2}{3}x-\frac{3}{2}x=\frac{5}{12}\)

\(\frac{4}{6}x-\frac{9}{6}x=\frac{5}{12}\)

\(\frac{-5}{6}x=\frac{5}{12}\)

\(x=\frac{5}{12}:\frac{-5}{6}\)

\(x=\frac{-1}{2}\)

\(b,\frac{2}{5}+\frac{3}{5}\cdot\left(3x-3,7\right)=\frac{-53}{10}\)

\(\frac{3}{5}\cdot\left(3x-3,7\right)=\frac{-53}{10}-\frac{2}{5}\)

\(\frac{3}{5}\cdot\left(3x-3,7\right)=\frac{-53}{10}-\frac{4}{10}\)

\(3x-3,7=\frac{-57}{10}:\frac{3}{5}\)

\(3x=\frac{-19}{2}+\frac{37}{10}\)

\(3x=\frac{-95}{10\text{​​}\text{​​}\text{​​}}+\frac{37}{10}\)

\(x=\frac{-29}{5}:3\)

\(x=\frac{-29}{15}\)

Answer 4

\(c,\frac{7}{9}:\left(2+\frac{3}{4}x\right)+\frac{5}{9}=\frac{23}{27}\)

\(\frac{7}{9}:\left(2+\frac{3}{4}x\right)=\frac{23}{27}-\frac{5}{9}\)

\(\frac{7}{9}:\left(2+\frac{3}{4}x\right)=\frac{23}{27}-\frac{15}{27}\)

\(2+\frac{3}{4}x=\frac{7}{9}:\frac{8}{27}\)

\(\frac{3}{4}x=\frac{21}{8}-2\)

\(x=\frac{5}{8}:\frac{3}{4}\)

\(x=\frac{5}{6}\)

\(b,\frac{-2}{3}\cdot x+\frac{1}{5}=\frac{3}{10}\)

\(\frac{-2}{3}\cdot x=\frac{3}{10}-\frac{1}{5}\)

\(\frac{-2}{3}\cdot x=\frac{3}{10}-\frac{2}{10}\)

\(x=\frac{1}{10}:\frac{-2}{3}\)

\(x=\frac{-3}{20}\)

Answer 5

câu d mình viết nhầm thành câu b mất rồi

Answer 6

\(e,\left|x\right|-\frac{3}{4}=\frac{5}{3}\)

\(\left|x\right|=\frac{5}{3}+\frac{3}{4}\)

\(\left|x\right|=\frac{20}{12}+\frac{9}{12}\)

\(\left|x\right|=\frac{11}{12}\)

⇒\(x=\frac{11}{12}\)hoặc\(x=\frac{-11}{12}\)

\(f,\left|2x-\frac{1}{3}\right|+\frac{5}{6}=1\)

\(\left|2x-\frac{1}{3}\right|=1-\frac{5}{6}\)

\(\left|2x-\frac{1}{3}\right|=\frac{1}{6}\)

\(\Rightarrow2x-\frac{1}{3}=\frac{1}{6}\)hoặc \(2x-\frac{1}{3}=\frac{-1}{6}\)

Ta có 2 trường hợp.

\(TH1.2x-\frac{1}{3}=\frac{1}{6}\) \(TH2.2x-\frac{1}{3}=\frac{-1}{6}\)

\(2x=\frac{1}{6}+\frac{1}{3}\) \(2x=\frac{-1}{6}+\frac{1}{3}\)

\(2x=\frac{1}{6}+\frac{2}{6}\) \(2x=\frac{-1}{6}+\frac{2}{6}\)

\(x=\frac{1}{2}:2\) \(x=\frac{-1}{6}:2\)

\(x=\frac{1}{4}\) \(x=\frac{1}{14}\)

Answer 7

Th1 tách khỏi Th2, đáp án Th2 là \(\frac{1}{12}\)