a, Hàm số xác định khi \(\left(x^2-1\right)^2-2x^2\ne0\)
\(\Leftrightarrow x^4-4x^2+1\ne0\)
\(\Leftrightarrow\left\{{}\begin{matrix}x\ne\frac{\pm\sqrt{6}-\sqrt{2}}{2}\\x\ne\frac{\pm\sqrt{6}+\sqrt{2}}{2}\end{matrix}\right.\)
\(\Rightarrow TXĐ:D=R\backslash\left\{\frac{\pm\sqrt{6}-\sqrt{2}}{2};\frac{\pm\sqrt{6}+\sqrt{2}}{2}\right\}\)
b, Hàm số xác định khi \(x^3+x^2-5x-2\ne0\)
\(\Leftrightarrow\left(x-2\right)\left(x^2+3x+1\right)\ne0\)
\(\Leftrightarrow\left\{{}\begin{matrix}x\ne2\\x\ne\frac{-3\pm\sqrt{5}}{2}\end{matrix}\right.\)
\(\Rightarrow TXĐ:D=R\backslash\left\{2;\frac{-3\pm\sqrt{5}}{2}\right\}\)
