Question

giải các phương trình sau:

a, √ 16x - 2√ x + √ 9x = 12

b, √ (4x² - 12x + 9) = 7

Answer 1

b: \(\Leftrightarrow\left|2x-3\right|=7\)

\(\Leftrightarrow\left[{}\begin{matrix}2x-3=7\\2x-3=-7\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=5\\x=-2\end{matrix}\right.\)

Answer 2

\(a,ĐK:x\ge0\\ PT\Leftrightarrow4\sqrt{x}-2\sqrt{x}+3\sqrt{x}=12\\ \Leftrightarrow5\sqrt{x}=12\Leftrightarrow\sqrt{x}=\dfrac{12}{5}\\ \Leftrightarrow x=\dfrac{144}{25}\left(tm\right)\\ b,PT\Leftrightarrow\sqrt{\left(2x-3\right)^2}=7\Leftrightarrow\left|2x-3\right|=7\\ \Leftrightarrow\left[{}\begin{matrix}2x-3=7\\3-2x=7\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=5\\x=-2\end{matrix}\right.\)