Question

Tìm x \(\in\) Q:

a) \(\frac{11}{12}-\left(\frac{2}{5}+x\right)=\frac{2}{3}\)b) \(2x\left(x-\frac{1}{7}\right)=0\)c) \(\frac{3}{4}+\frac{1}{8}.x=\frac{2}{5}\)

Answer 1

Answer 2

Answer 3

Answer 4

a,\(\frac{11}{12}-\left(\frac{2}{5}+x\right)=\frac{2}{3}\)

    \(\frac{2}{5}+x=\frac{11}{12}-\frac{2}{3}\)

    \(\frac{2}{5}+x=\frac{1}{4}\)

           \(x=\frac{1}{4}-\frac{2}{5}\)

           \(x=\frac{-3}{20}\)

b,\(2x\left(x-\frac{1}{7}\right)=0\)

<=>\(\left[\begin{array}{nghiempt}2x=0\\x-\frac{1}{7}=0\end{array}\right.\) <=>\(\left[\begin{array}{nghiempt}x=0\\x=\frac{1}{7}\end{array}\right.\)

Vậy x=0 hoặc x=\(\frac{1}{7}\)

c,\(\frac{3}{4}+\frac{1}{8}.x=\frac{2}{5}\)

  \(\frac{1}{8}.x=\frac{2}{5}-\frac{3}{4}\)

   \(\frac{1}{8}.x=-\frac{7}{20}\)

        \(x=-\frac{14}{5}\)

Chúc bạn học tốt!

 

Answer 5

Answer 6

a) \(\frac{11}{12}-\left(\frac{2}{5}+x\right)=\frac{2}{3}\)

\(\Rightarrow\frac{11}{12}-\frac{2}{5}-x=\frac{2}{3}\)

\(\Rightarrow\frac{31}{60}-x=\frac{2}{3}\)

\(\Rightarrow x=\frac{31}{60}-\frac{2}{3}\)

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

b) \(2x\left(x-\frac{1}{7}\right)=0\)

\(\Rightarrow\left[\begin{array}{nghiempt}2x=0\\x-\frac{1}{7}=0\end{array}\right.\)

\(\Rightarrow\left[\begin{array}{nghiempt}x=0\\x=\frac{1}{7}\end{array}\right.\)

c) \(\frac{3}{4}+\frac{1}{8}.x=\frac{2}{5}\)

\(\Rightarrow\frac{1}{8}.x=\frac{2}{5}-\frac{3}{4}\)

\(\Rightarrow\frac{1}{8}.x=-\frac{7}{20}\)

\(\Rightarrow x=-\frac{7}{20}:\frac{1}{8}\)

\(\Rightarrow x=-\frac{14}{5}\)