2025 JPJC P1 Q9

2025 JPJC P1 Q9

11 marks

It is given that \(\mathrm{f}(x) = \frac{1}{4+9x^2}\).

  1. Find \(\displaystyle \displaystyle\int \mathrm{f}(x) \, \mathrm{d}x\).[2]
  2. Find the binomial expansion for \(\mathrm{f}(x)\), up to and including the term in \(x^4\). Give the coefficients as exact fractions in their simplest form.[2]
  3. Hence, find the Maclaurin series for \(\tan^{-1} \frac{3x}{2}\). Give the coefficients as exact fractions in their simplest form.[3]
  4. Use your series from part (c) to estimate \(\displaystyle \displaystyle\int_{0}^{0.5} \tan^{-1} \frac{3x}{2} \, \mathrm{d}x\), correct to \(3\) decimal places.[1]
  5. Use your calculator to find \(\displaystyle \displaystyle\int_{0}^{0.5} \tan^{-1} \frac{3x}{2} \, \mathrm{d}x\), correct to \(3\) decimal places.[1]
  6. Comparing your answers to parts (d) and (e), comment on the accuracy of your estimate in (e) and how it can be improved.[2]
Similar questions are unavailable for this question.
Answer:(a)\(\frac{1}{6}\tan ^{-1}\frac{3x}{2}+K\) (b)\(\frac{1}{4}-\frac{9}{16}x^2+\frac{81}{64}x^4\) (c)\(\tan^{-1} \frac{3x}{2} = \frac{3}{2}x - \frac{9}{8}x^3 + \frac{243}{160}x^5\) (d)0.174 (e)0.173

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