a ) \(1+\sqrt{3x+1}=3x\) ( ĐKXĐ : \(x\ge-\dfrac{1}{3}\) )
\(\Leftrightarrow\sqrt{3x+1}=3x-1\)
\(\Leftrightarrow3x+1=\left(3x-1\right)^2\)
\(\Leftrightarrow3x+1-\left(3x-1\right)^2=0\)
\(\Leftrightarrow3x+1-9x^2+6x-1=0\)
\(\Leftrightarrow9x^2-9x=0\)
\(\Leftrightarrow9x\left(x-1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}9x=0\\x-1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\left(tm\right)\\x=1\left(tm\right)\end{matrix}\right.\)
Vậy phương trình có nghiệm x = 0 hoặc x = 1 .
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