a) 8/23 . 46/24 = 1/3 . x b) 1/5 : x = 1/5 – 1/7 c) 4/9 – (x – 1/2) mũ 2 = 1/3 d)3,2 . x – (4/5 + 2/3) : 3 2/3 = 7/10

Giải đáp: $\begin{array}{l}
a)x = 2\\
b)x = \dfrac{7}{2}\\
c)x = \dfrac{5}{6};x = \dfrac{1}{6}\\
d)x = \dfrac{{11}}{{32}}
\end{array}$

 

Lời giải và giải thích chi tiết:

$\begin{array}{l}
a)\dfrac{8}{{23}}.\dfrac{{46}}{{24}} = \dfrac{1}{3}.x\\
 \Leftrightarrow \dfrac{2}{3} = \dfrac{1}{3}.x\\
 \Leftrightarrow x = \dfrac{2}{3}.3\\
 \Leftrightarrow x = 2\\
Vậy\,x = 2\\
b)\dfrac{1}{5}:x = \dfrac{1}{5} – \dfrac{1}{7}\\
 \Leftrightarrow \dfrac{1}{5}:x = \dfrac{2}{{35}}\\
 \Leftrightarrow x = \dfrac{1}{5}:\dfrac{2}{{35}}\\
 \Leftrightarrow x = \dfrac{1}{5}.\dfrac{{35}}{2}\\
 \Leftrightarrow x = \dfrac{7}{2}\\
Vậy\,x = \dfrac{7}{2}\\
c)\dfrac{4}{9} – {\left( {x – \dfrac{1}{2}} \right)^2} = \dfrac{1}{3}\\
 \Leftrightarrow {\left( {x – \dfrac{1}{2}} \right)^2} = \dfrac{4}{9} – \dfrac{1}{3}\\
 \Leftrightarrow {\left( {x – \dfrac{1}{2}} \right)^2} = \dfrac{1}{9}\\
 \Leftrightarrow \left[ \begin{array}{l}
x – \dfrac{1}{2} = \dfrac{1}{3}\\
x – \dfrac{1}{2} =  – \dfrac{1}{3}
\end{array} \right.\\
 \Leftrightarrow \left[ \begin{array}{l}
x = \dfrac{1}{3} + \dfrac{1}{2} = \dfrac{5}{6}\\
x =  – \dfrac{1}{3} + \dfrac{1}{2} = \dfrac{1}{6}
\end{array} \right.\\
Vậy\,x = \dfrac{5}{6};x = \dfrac{1}{6}\\
d)3,2.x – \left( {\dfrac{4}{5} + \dfrac{2}{3}} \right):3\dfrac{2}{3} = \dfrac{7}{{10}}\\
 \Leftrightarrow 3,2.x – \dfrac{{22}}{{15}}:\dfrac{{11}}{3} = \dfrac{7}{{10}}\\
 \Leftrightarrow \dfrac{{16}}{5}.x – \dfrac{{22}}{{15}}.\dfrac{3}{{11}} = \dfrac{7}{{10}}\\
 \Leftrightarrow \dfrac{{16}}{5}.x – \dfrac{2}{5} = \dfrac{7}{{10}}\\
 \Leftrightarrow \dfrac{{16}}{5}.x = \dfrac{7}{{10}} + \dfrac{2}{5}\\
 \Leftrightarrow \dfrac{{16}}{5}.x = \dfrac{{11}}{{10}}\\
 \Leftrightarrow x = \dfrac{{11}}{{10}}.\dfrac{5}{{16}}\\
 \Leftrightarrow x = \dfrac{{11}}{{32}}\\
Vậy\,x = \dfrac{{11}}{{32}}
\end{array}$