Final answer:
The indefinite integral, or antiderivative, of a constant function is the function itself multiplied by x.
Step-by-step explanation:
The indefinite integral, also known as the antiderivative, represents the reverse process of differentiation. To find the indefinite integral of a given function, we need to find a function whose derivative is equal to the given function. In this case, we are asked to find the indefinite integral of the function.
Since the given function is a constant, the indefinite integral will be the function itself multiplied by x. Hence, the indefinite integral of the given function is f(x) = 20x + C, where C is the constant of integration.