A-level · Integration

The constant of integrationExam-style questions

Why every indefinite integral carries a + C — differentiation loses the constant, so integrating gives a family of curves. Reading the family as one shape at every height; finding the curve through a given point; starting values in motion, and why C is not always zero; two constants when you integrate twice; and why a definite integral needs no constant.

9 questions · A-level level · mark scheme and worked solution on each · no sign-up to try

DifficultyAllLevel 3Level 4
  1. 1
    A curve passes through (1,4)(1, 4) and has dydx=2x\dfrac{\mathrm{d}y}{\mathrm{d}x} = 2x. Find yy in terms of xx.
    Level 3 · 4 marksTry it
  2. 2
    A curve passes through (2,5)(2, 5) and has dydx=3x2−2\dfrac{\mathrm{d}y}{\mathrm{d}x} = 3x^2 - 2. Find yy.
    Level 3 · 4 marksTry it
  3. 3
    A curve passes through (0,3)(0, 3) and has dydx=4x−1\dfrac{\mathrm{d}y}{\mathrm{d}x} = 4x - 1. Find yy.
    Level 3 · 4 marksTry it
  4. 4
    A curve CC has equation y=f(x)y = \text{f}(x), where

    f′(x)=4x3−6x2+3x+k\text{f}'(x) = 4x^3 - 6x^2 + 3x + k

    and kk is a constant.

    The point Q(2,−6)Q(2, -6)
    • lies on CC
    • is a turning point of CC
    (a) Show that k=−14k = -14

    (2 marks)

    The curve CC cuts the yy-axis at the point RR.
    (b) Hence find the coordinates of RR.

    (3 marks)
    Level 3 · 5 marksTry it
  5. 5
    Given f′(x)=6x2+2f'(x) = 6x^2 + 2 and f(1)=5f(1) = 5, find f(x)f(x).
    Level 4 · 4 marksTry it

4 more questions on the constant of integration

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