a) \(\left\{{}\begin{matrix}x^2+3y=1\\3x^2-y=1\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x^2+3y=1\\9x^2-3y=3\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}10x^2=4\\y=3x^2-1\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x=\dfrac{\sqrt{10}}{5}\\y=\dfrac{1}{5}\end{matrix}\right.\\\left\{{}\begin{matrix}x=\dfrac{-\sqrt{10}}{5}\\y=\dfrac{1}{5}\end{matrix}\right.\end{matrix}\right.\)
mk ko chắc đâu nha
\(x+\left|x-1\right|>5\)
\(\Leftrightarrow\left|x-1\right|>5-x\)
\(\Leftrightarrow\left(x-1\right)^2>\left(5-x\right)^2\)
\(\Leftrightarrow x^2-2x+1>x^2-10x+25\)
\(\Leftrightarrow x>3\)
