N2009 P1 Q11

N2009 P1 Q11

Junior College 2
14 marks

The curve \(C\) has equation \(y=f(x)\), where \(f(x)=x\mathrm e^{-x^2}\).

  1. Sketch the curve C.[2]
  2. Find the exact coordinates of the turning points on the curve.[4]
  3. Use the substitution \(u=x^2\) to find \(\int_0^n f(x)\,\mathrm dx\), for \(n>0\). Hence find the area of the region between the curve and the positive \(x\)-axis.[4]
  4. Find the exact value of \(\int_{-2}^2|f(x)|\,\mathrm dx\).[2]
  5. Find the volume of revolution when the region bounded by the curve, the lines \(x=0\), \(x=1\) and the \(x\)-axis is rotated completely about the \(x\)-axis. Give your answer correct to 3 significant figures.[2]

Solution:

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Finding similar questions...
Answer:(ii) \((\pm1/\sqrt2,\pm1/\sqrt{2\mathrm e})\). (iii) \(\frac12(1-\mathrm e^{-n^2})\), area \(\frac12\). (iv) \(1-\mathrm e^{-4}\). (v) \(0.363\).

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