$$\frac{ { x }^{ 4 } +2 { x }^{ 3 } -3 { x }^{ 2 } }{ { x }^{ 4 } +2 { x }^{ 3 } +2 { x }^{ 2 } +10x+15 }$$
$\frac{\left(x-1\right)\left(x+3\right)x^{2}}{x^{4}+2x^{3}+2x^{2}+10x+15}$
$\frac{x^{4}+2x^{3}-3x^{2}}{x^{4}+2x^{3}+2x^{2}+10x+15}$
