(A34) 2 c P nRT P dP nRT +=− ∫ 7/10/07 A- 131 There are times, however, when we are more interested in finding the function from which the integrand came (i.e., finding the antiderivative) than in finding the actual change. Then we must recognize that the derivative of a constant is zero, so any arbitrary constant added to the integral vanishes in finding the integrand. Thus we may write where c is an arbitrary, or unknown, constant. Such an expression is called an indefinite integral. . 131 There are times, however, when we are more interested in finding the function from which the integrand came (i.e., finding the antiderivative) than in finding the actual change. Then we must. change. Then we must recognize that the derivative of a constant is zero, so any arbitrary constant added to the integral vanishes in finding the integrand. Thus we may write where c is an arbitrary,. we may write where c is an arbitrary, or unknown, constant. Such an expression is called an indefinite integral.