\(\left|x+5\right|=3x+1\)
t/hợp 1: \(x+5\ge0\Leftrightarrow x\le5\)
\(\Rightarrow x+5=3x+1\)
\(\Leftrightarrow5-1=3x-x\Leftrightarrow4=2x\)
\(\Leftrightarrow x=2\left(TMĐK\right)\)
t/hợp 2: \(x+5\)<0 \(\Leftrightarrow\)x>5
\(\Leftrightarrow-\left(x+5\right)=3x+1\)
\(-x-5=3x+1\)\(\Leftrightarrow-x-3x=5+1\Leftrightarrow-4x=6\Leftrightarrow x=-\dfrac{3}{2}\)
-Bạn tự giải mà giải còn sai nữa :v
-ĐKXĐ: \(3x+1\ge0\Leftrightarrow3x\ge-1\Leftrightarrow x\ge\dfrac{-1}{3}\)
\(\left|x+5\right|=3x+1\)
\(\Leftrightarrow\left[{}\begin{matrix}x+5=3x+1\\x+5=-3x-1\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x-3x=1-5\\x+3x=-1-5\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}-2x=-4\\4x=-6\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=2\left(nhận\right)\\x=\dfrac{-3}{2}\left(loại\right)\end{matrix}\right.\)
-Vậy \(S=\left\{2\right\}\)
