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Partial fractions and reduction formulaeAQA A-Level Further Maths: Flashcards

What these 12 flashcards ask

  • Partial fraction form for \dfrac{px+q}{(x-a)(x-b)}?
  • Partial fraction form when the denominator contains x^2+c?
  • \displaystyle\int\frac{k}{ax+b}\,dx?
  • \displaystyle\int\frac{x}{x^2+c}\,dx?
  • \displaystyle\int\frac{1}{x^2+c}\,dx for c0?
  • Two ways to find partial fraction constants?
  • What is a reduction formula?
  • Reduction formula for \int0^1x^ne^x\,dx?
  • Reduction formula for \int0^{\pi/2}\sin^nx\,dx?
  • Technique used to derive most reduction formulae?
  • Values of I0 and I1 for \int0^{\pi/2}\sin^nx\,dx?
  • How are \ln p+\ln q and k\ln p combined?

Exam questions on Partial fractions and reduction formulae

  1. Let f(x)=5x+1(x−1)(x+2)\mathrm{f}(x)=\dfrac{5x+1}{(x-1)(x+2)}.
    Find the exact value of ∫23f(x) dx\int_2^3\mathrm{f}(x)\,dx, giving your answer as a single logarithm.2 marks
  2. Let g(x)=5x2+4x+9(x+1)(x2+4)\mathrm{g}(x)=\dfrac{5x^2+4x+9}{(x+1)(x^2+4)}, and let g(x)≡Ax+1+Bx+Cx2+4\mathrm{g}(x)\equiv\dfrac{A}{x+1}+\dfrac{Bx+C}{x^2+4}.
    Find the exact value of ∫023xx2+4 dx\displaystyle\int_0^2\frac{3x}{x^2+4}\,dx, giving your answer in the form pln⁡qp\ln q.2 marks
  3. For integer n≥0n\ge0, let In=∫01xnex dxI_n=\int_0^1x^n\mathrm{e}^x\,dx.
    Show that In=e−nIn−1I_n=\mathrm{e}-nI_{n-1} for n≥1n\ge1.3 marks
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Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).