Toán Lớp 7: Tìm x
27 : ( x – $\frac{3}{2}$ ) = ( x – $\frac{3}{2} $)^3 : 3
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Toán Lớp 7: Tìm x
27 : ( x – $\frac{3}{2}$ ) = ( x – $\frac{3}{2} $)^3 : 3
Comments ( 1 )
x = \dfrac{9}{2}\\
x = – \dfrac{3}{2}
\end{array} \right.\)
DK:x \ne \dfrac{3}{2}\\
27:\left( {x – \dfrac{3}{2}} \right) = {\left( {x – \dfrac{3}{2}} \right)^3}:3\\
\to \dfrac{{27}}{{x – \dfrac{3}{2}}} = \dfrac{{{{\left( {x – \dfrac{3}{2}} \right)}^3}}}{3}\\
\to {\left( {x – \dfrac{3}{2}} \right)^4} = 27.3\\
\to {\left( {x – \dfrac{3}{2}} \right)^4} = {3^3}.3\\
\to {\left( {x – \dfrac{3}{2}} \right)^4} = {3^4}\\
\end{array}\)
\to \left[ \begin{array}{l}
x – \dfrac{3}{2} = 3\\
x – \dfrac{3}{2} = – 3
\end{array} \right.\\
\to \left[ \begin{array}{l}
x = \dfrac{9}{2}\\
x = – \dfrac{3}{2}
\end{array} \right.
\end{array}\)