[tex]\displaystyle\bf\\1)\\\\\frac{3}{x-4} +\frac{4x-6}{x^{2} -3x-4} +\frac{2x}{x+1}=\frac{3}{x-4} +\frac{4x-6}{(x-4)\cdot(x+1)} +\frac{2x}{x+1}=\\\\\\=\frac{3\cdot(x+1)+4x-6+2x\cdot(x-4)}{(x-4)\cdot(x+1)} =\\\\\\=\frac{3x+3+4x-6+2x^{2} -8x}{(x-4)\cdot(x+1)} =\frac{2x^{2} -x-3}{(x-4)(x+1)} =\\\\\\=\frac{2\cdot(x-1,5)(x+0,5)}{(x-4)(x+1)}=\frac{(2x-3)(x+0,5)}{(x-4)(x+1)} \\\\2)\\\\\frac{(2x-3)(x+0,5)}{(x-4)(x+1)}\cdot\frac{x}{2x-3} =\frac{x(x+0,5)}{x^{2}-3x-4 }[/tex]