$$\frac{ t-1 }{ { t }^{ 4 } +6 { t }^{ 3 } +9 { t }^{ 2 } }$$
$\frac{t-1}{\left(t\left(t+3\right)\right)^{2}}$
$\frac{t-1}{t^{4}+6t^{3}+9t^{2}}$
