By definition, a rational function, is an algebraic expression that includes a term in fractional form containing polynomials. To illustrate more clearly, this is an example of a rational function:

Basically, a rational function must have polynomials in both the numerator and denominator of the fractional term. Since the given function f(x)= 6x-2/5 only contains a polynomial on the numerator, this is not a rational function. The denominator is a constant, not a polynomial.
The answer is false.