Question

 b/ 2x.(x-1/7)=0

d/3/4+1/4:x=2/5

 

Answer 1

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

\(\Leftrightarrow\left[{}\begin{matrix}2x=0\\x-\dfrac{1}{7}=0\end{matrix}\right.\)\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=\dfrac{1}{7}\end{matrix}\right.\)

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

\(\Leftrightarrow\dfrac{1}{4}:x=-\dfrac{7}{20}\)

\(\Leftrightarrow x=\dfrac{1}{4}:\left(-\dfrac{7}{20}\right)=-\dfrac{5}{7}\)