Using the appropriate theorems, explain why the function is continuous at every number in its domain. F ( x ) = 2x2 - x - 7 x- + 1 OF(x) is a polynomial, so it is continuous at every number in its domain. . OF(x) is a rational function, so it is continuous at every number in its domain. OF(x) is a composition of functions that are continuous for all real numbers, so it is continuous at every number in its domain O F(x) is not continuous at every number in its domain. O none of these Find the domain. (Enter your answer using interval notation.)