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IB Mathematics: Applications and Interpretation HL · AHL 3: Further Integration · AHL 3.3

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Further integration: practice Problem set B

Show the substitution or the rule you use. Add + c to every indefinite integral. Use a boundary condition to find c. Give exact answers unless the question asks for 3 significant figures.

Each question matches the question with the same number in set A. Do the ones you got wrong there.

Difficulty: first skills applying them stretch

Skills

  1. \(\frac{dy}{dx}=21\sqrt{x}\), and y = 400 when x = 9. Find y in terms of x.

  2. Find the required function in each case.

    1. (a) \(f'(x)=4\cos x-7\sin x\) and f(0) = 10. Find f(x).
    2. (b) \(\frac{dy}{dx}=5e^x-\frac{2}{x}\) for x > 0, and y = 1 when x = 1. Find y in terms of x.
    3. (c) \(\int\frac{8x^2+6}{2x}\,dx\)
  3. Find each integral.

    1. (a) \(\int(2-5x)^{7}\,dx\)
    2. (b) \(\int(5\sin(3x)+4\cos(6x))\,dx\)
    3. (c) \(\int 4x(x^2+2)^{6}\,dx\)
  4. Find each integral.

    1. (a) \(\int x^2\sqrt{3x^3+7}\,dx\)
    2. (b) \(\int x\sqrt[3]{5-3x^2}\,dx\)
  5. Find each integral.

    1. (a) \(\int 14xe^{4x^2}\,dx\)
    2. (b) \(\int 9x^4e^{-3x^5}\,dx\)
  6. Find each integral.

    1. (a) \(\int\frac{x^4}{3x^5+2}\,dx\)
    2. (b) \(\int\frac{x}{5-2x^2}\,dx\)
  7. Use a substitution to find the following.

    1. (a) \(\frac{dy}{dx}=x\cos(4x^2)\). Find y in terms of x.
    2. (b) \(\int\frac{6x}{\sqrt{3x^2+1}}\,dx\)

In context

  1. Air is pumped into a balloon. After t seconds the volume of air is V cm³, and \(\frac{dV}{dt}=0.9t^2+3\) and V = 20 when t = 0.

    1. (a) Find an expression for \(V\) in terms of t.
    2. (b) Find the volume when t = 4.
  2. The depth of a submarine below the surface is x metres at time t minutes, and \(\frac{dx}{dt}=15-4e^t\) and x = 30 when t = 0.

    1. (a) Find an expression for \(x\) in terms of t.
    2. (b) Find the depth when t = 2.

Stretch

  1. Find f(x) in each case.

    1. (a) \(f'(x)=\frac{4}{(3x-2)^2}\), and the graph of y = f(x) passes through the point (2, 1). Find f(x).
    2. (b) \(f'(x)=\frac{3\ln x}{4x}\) for x > 0, and the curve y = f(x) passes through the point \((e^2, 6)\). Find f(x).
  2. \(f'(x)=\frac{5}{x}\) and f(-3) = 2. Find the exact value of \(f(-7)\).

  3. Find each integral.

    1. (a) \(\int\left(10\cos^4 x\sin x+kx^{2}+3\right)dx\), where k is a constant.
    2. (b) \(\int\frac{e^{3x}+e^{-x}}{e^{x}}\,dx\)
  4. Find each integral.

    1. (a) \(\int\sqrt{x^4+8x^2}\,dx\) for x > 0.
    2. (b) \(\int\frac{4}{x\ln x}\,dx\) for x > 1.
  5. Find each integral.

    1. (a) Given that \(\cos 2x=1-2\sin^2x\), find \(\int 8\sin^2x\,dx\).
    2. (b) \(\int\tan 4x\,dx\), showing your working.
    3. (c) \(\int 3\cos^3x\,dx\)

jmaths.xyz · AI HL · AHL 3.3 Further integration: substitution and boundary conditions