Home / Calculus / Introductory Ideas / First Calculations; Linear Approximations, Differentials A. First Calculations; Linear Approximations, Differentials First calculations, linear approximations, and differentials. Topics in this Section A.1 First Calculations A.2 Generalizing to Other Rates of Change A.3 Introducing Linear Approximations A.4 Practice Problems: Linear Approximations A.5 Differentials; Steps Toward Determining df/dx at x=a A.6 Estimating df/dx at x=a Graphically