[tex]\frac{x ^ 2-4 }{x ^ 2-1}*\frac{ x + 1 }{x ^ 2 +2 x}=\frac{x ^ 2-2^2 }{x ^ 2-1}*\frac{ x + 1 }{x(x +2 )} =\\ \\ \\ =\frac{(x -2)\not(x+2)^1 }{(x -1)\not(x+1)^1}*\frac{ \not(x + 1)^1 }{x\not(x +2)^1 }= \frac{ x-2 }{x(x-1)} \\ \\ \\ \\a^2-b^2 =(a-b)(a+b)[/tex]
