Abstract Algebra question: If F(x) is the field of rational functions with coefficients in a field F, what is F(x)[t]?

Question

The problem I'm working on involves proving that the polynomial t^n-x is irreducible in F(x)[t], and while I understand how F(x) is defined, I'm not really how to understand really what F(x)[t] is.

Answer 1

It's the ring of polynomials (in the variable $t$) whose coefficients are rational functions (in the variable $x$) with coefficients in $F$.

For example $$ t^2 + \frac{x+1}{x^2 + 1}t + x $$