Giải thích các bước giải:
\(\begin{array}{l}
2)DK:x \ne - 1;x \ne 1\\
Xét:\left[ \begin{array}{l}
2 - x = 0\\
3x - 9 = 0
\end{array} \right. \to \left[ \begin{array}{l}
x = 2\\
x = 3
\end{array} \right.
\end{array}\)
BXD:
x -∞ -1 1(kép) 2 3 +∞
g(x) + // - // - 0 + 0 -
\(\begin{array}{l}
3)DK:x \ne - 3\\
Xét:\left[ \begin{array}{l}
9 - x = 0\\
11x + 2 = 0
\end{array} \right. \to \left[ \begin{array}{l}
x = 9\\
x = - \frac{2}{{11}}
\end{array} \right.
\end{array}\)
BXD:
x -∞ -3 -2/11 9 +∞
h(x) + // - 0 + 0 -
\(4)Xét:\left[ \begin{array}{l}
x = 0\\
{x^2} + 4x - 5 = 0
\end{array} \right. \to \left[ \begin{array}{l}
x = 0\\
x = - 5\\
x = 1
\end{array} \right.\)
BXD:
x -∞ -5 0 1 +∞
k(x) - 0 + 0 - 0 +
