Toán Lớp 8: giúp mk với nhé!!!
(4x-5)^2-81=0
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Toán Lớp 8: giúp mk với nhé!!!
(4x-5)^2-81=0
Comments ( 2 )
{\left( {4x – 5} \right)^2} – 81 = 0\\
\Rightarrow {\left( {4x – 5} \right)^2} = 81\\
\Rightarrow {\left( {4x – 5} \right)^2} = {9^2}\\
\Rightarrow \left| {4x – 5} \right| = 9\\
\Rightarrow \left[ \begin{array}{l}
4x – 5 = 9\\
4x – 5 = – 9
\end{array} \right. \Rightarrow \left[ \begin{array}{l}
x = \frac{7}{2}\\
x = – 1
\end{array} \right.
\end{array}\]
x = \dfrac{7}{2}\\
x = – 1
\end{array} \right.\)
{(4x – 5)^2} – 81 = 0\\
\to {(4x – 5)^2} = 81\\
\to \left| {4x – 5} \right| = 9\\
\to \left[ \begin{array}{l}
4x – 5 = 9\\
4x – 5 = – 9
\end{array} \right.\\
\to \left[ \begin{array}{l}
x = \dfrac{7}{2}\\
x = – 1
\end{array} \right.
\end{array}\)