Question

giải pt sau:

\(\left|x^2-2x-1\right|=14\)

Answer 1

\(\Leftrightarrow\left[{}\begin{matrix}x^2-2x-1=14\\x^2-2x-1=-14\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x^2-2x-15=0\\x^2-2x+13=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}\left(x-5\right)\left(x+3\right)=0\\\left(x-1\right)^2+12=0\left(vô-nghiệm\right)\end{matrix}\right.\)

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