Tìm ĐKXĐ và rút gọn biểu thức \(P\)
A.ĐKXĐ: \(\left\{ \begin{array}{l}x \ne - 1\\x \ne \pm 3\end{array} \right.\,\,\,;\,\,\,\,P = \frac{{x + 1}}{{x + 3}}\)
B.ĐKXĐ: \(\left\{ \begin{array}{l}x \ne \pm 1\\x \ne 3\end{array} \right.\,\,\,;\,\,\,\,P = \frac{{x + 1}}{{3 - x}}\)
C.ĐKXĐ: \(\left\{ \begin{array}{l}x \ne - 1\\x \ne \pm 3\end{array} \right.\,\,\,;\,\,\,\,P = \frac{{x + 3}}{{x + 1}}\)
D.ĐKXĐ: \(\left\{ \begin{array}{l}x \ne \pm 1\\x \ne 3\end{array} \right.\,\,\,;\,\,\,\,P = \frac{{3 - x}}{{x + 1}}\)