Math Question!!!

t³ + tu + u²

        t

Thanks JadeFrost and welcome to the forum :)

t^2-u^2/t+u

I expect that you actually mean  (t^2-u^2) / (t+u)         

\(\frac{(t^2-u^2) }{ (t+u) }\\ =\frac{(t-u)(t+u) }{ (t+u) }\\ =\frac{(t-u)}{ 1 }\\ =t-u\)