I need help with this question

solve 15t^2 + 2t + 5 = 3t(t^2 + 1).

Multiply out (Distribute on Right Hand Side). This gives

15t^2 + 2t + 5 = 3t^3 + 3t

That is,

0 = 3t^3 - 15t^2 + t - 5

(bring everything to the right hand side).

Now, factor the right hand side by grouping.

0 = (3t^3 - 15t^2) + (t -5)

0 = 3t^2(t - 5) + 1(t-5)

Go from here now.