Giải thích các bước giải:
Ta có:
\(\begin{array}{l}
a,\\
\dfrac{4}{3} - \dfrac{1}{2}x = \dfrac{{49}}{9}\\
\Leftrightarrow \dfrac{1}{2}x = \dfrac{4}{3} - \dfrac{{49}}{9}\\
\Leftrightarrow \dfrac{1}{2}x = - \dfrac{{37}}{9}\\
\Leftrightarrow x = \left( { - \dfrac{{37}}{9}} \right):\dfrac{1}{2}\\
\Leftrightarrow x = - \dfrac{{74}}{9}\\
b,\\
{x^3} = {x^2}\\
\Leftrightarrow {x^3} - {x^2} = 0\\
\Leftrightarrow {x^2}\left( {x - 1} \right) = 0\\
\Leftrightarrow \left[ \begin{array}{l}
{x^2} = 0\\
x - 1 = 0
\end{array} \right. \Leftrightarrow \left[ \begin{array}{l}
x = 0\\
x = 1
\end{array} \right.\\
c,\\
{27^x}:{3^x} = 9\\
\Leftrightarrow {\left( {27:3} \right)^x} = 9\\
\Leftrightarrow {9^x} = 9\\
\Leftrightarrow x = 1\\
d,\\
{64^x}:{4^{x + 2}} = 16\\
\Leftrightarrow {\left( {{4^3}} \right)^x}:{4^{x + 2}} = {4^2}\\
\Leftrightarrow {4^{3x}}:{4^{x + 2}} = {4^2}\\
\Leftrightarrow {4^{3x - \left( {x + 2} \right)}} = {4^2}\\
\Leftrightarrow {4^{2x - 2}} = {4^2}\\
\Leftrightarrow 2x - 2 = 2\\
\Leftrightarrow x = 2\\
e,\\
\dfrac{{81}}{{{3^x}}} = 9\\
\Leftrightarrow {3^x} = 81:9\\
\Leftrightarrow {3^x} = 9\\
\Leftrightarrow {3^x} = {3^2}\\
\Leftrightarrow x = 2
\end{array}\)
