Salam Academy
Paper 2 · Module

Further calculus

3 subtopics≈ 135 min in total
  1. Volumes, mean values and improper integrals

    Spin a curve about an axis and the solid's volume is π∫y2 dx\pi\int y^2\,dx (or π∫x2 dy\pi\int x^2\,dy). The mean value of ff on [a,b][a,b] is 1b−a∫abf dx\frac1{b-a}\int_a^bf\,dx. An improper integral has an infinite limit or an infinite integrand: replace it by a limit and see whether that limit exists.

    ≈ 45 min
  2. Inverse trig and hyperbolic functions in calculus

    Differentiating y=arcsin⁡xy=\arcsin x implicitly gives 11−x2\frac1{\sqrt{1-x^2}}; similar results hold for arctan⁡\arctan, arsinh⁡\operatorname{arsinh}, arcosh⁡\operatorname{arcosh}. Read backwards, these give the integrals of 1a2−x2\frac1{\sqrt{a^2-x^2}}, 1a2+x2\frac1{a^2+x^2} and 1x2±a2\frac1{\sqrt{x^2\pm a^2}}, which algebra alone can't do.

    ≈ 45 min
  3. Maclaurin series

    Any smooth function can be approximated near 00 by a polynomial whose derivatives match it there: f(x)=f(0)+f′(0)x+f′′(0)2!x2+⋯f(x)=f(0)+f'(0)x+\frac{f''(0)}{2!}x^2+\cdots. Standard series for exe^x, sin⁡x\sin x, cos⁡x\cos x, ln⁡(1+x)\ln(1+x) and (1+x)n(1+x)^n combine by substitution, multiplication and differentiation.

    ≈ 45 min