Explain, using the theorems, why the function is continuous at every number in its domain. M(x) = 1 + 9 x M(x) is a polynomial, so it is continuous at every number in its domain. M(x) is a rational function, so it is continuous at every number in its domain. M(x) is a composition of functions that are continuous, so it is continuous at every number in its domain. M(x) is not continuous at every number in its domain. none of these