A-level · Algebra & functions

Sketching curvesExam-style questions

Drawing a curve from its equation without plotting points. Where it meets the axes, read from the factors; which way the ends go, from the leading term; whether it crosses or touches at each root; reciprocal curves and their asymptotes; finding where two curves meet; and counting meeting points from a sketch or with the discriminant.

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

DifficultyAllLevel 2Level 3Level 4Level 5
  1. 1
    The function f is defined by

    f(x)=x(x+a)(x+5)for x∈R\mathrm{f}(x) = x(x + a)(x + 5) \quad \text{for } x \in \mathbb{R}

    where aa is a constant and 0<a<50 < a < 5
    (a) Sketch the graph of y=f(x)y = \mathrm{f}(x)

    (3 marks)
    (b) Sketch the graph of y=f(−3x)y = \mathrm{f}(-3x)

    (2 marks)
    Level 4 · 5 marksTry it
  2. 2
    (a) Sketch the graph of

    y=1x3y = \frac{1}{x^3}

    (2 marks)
    (b) The graph of y=1x3y = \dfrac{1}{x^3} is to be transformed into the graph of y=64x3y = \dfrac{64}{x^3} using one stretch.

    Rhys says that this can be done with a stretch parallel to the yy-axis.

    Isla says that this can be done with a stretch parallel to the xx-axis.

    State whether Rhys is correct, Isla is correct, both are correct or neither is correct, giving reasons for your answer.

    (3 marks)
    Level 4 · 5 marksTry it
  3. 3
    OA(4, 32)B(12, 0)xyFigure 1

    Figure 1 shows a sketch of the curve CC with equation y=f(x)y = \text{f}(x), where f(x)\text{f}(x) is a cubic polynomial.

    The curve passes through the origin OO. The point A(4, 32)A(4,\ 32) is a maximum point of CC and the point B(12, 0)B(12,\ 0) is a minimum point of CC.
    (a) Write down the set of values of xx for which f′(x)<0\text{f}'(x) < 0

    (1 mark)

    The line ll, with equation y=ky = k where kk is a constant, meets CC at one point only.
    (b) Find the set of values of kk, giving your answer in set notation.

    (2 marks)
    (c) Find the equation of CC. You may leave your answer in factorised form.

    (3 marks)
    Level 4 · 6 marksTry it
  4. 4
    OP(−6, −18)xyFigure 1

    Figure 1 shows a sketch of the curve CC with equation y=h(x)y = \text{h}(x), where h(x)\text{h}(x) is a polynomial of degree 3.

    The curve has a minimum point at P(−6, −18)P(-6,\ -18) and a maximum point at the origin OO.
    (a) Write down the set of values of xx for which h′(x)<0\text{h}'(x) < 0

    (1 mark)

    Given that the curve CC and the line with equation y=ky = k, where kk is a constant, have exactly one point in common,
    (b) find the set of values of kk, giving your answer in set notation.

    (2 marks)
    (c) Find the equation of CC. You may leave your answer in factorised form.

    (3 marks)
    Level 4 · 6 marksTry it
  5. 5
    The curve CC has equation y=x+2x−1y = \dfrac{x + 2}{x - 1}.
    (a) Write down the equations of the vertical and horizontal asymptotes of CC. (2 marks)
    (b) Find the coordinates of the points where CC crosses the coordinate axes. (2 marks)
    (c) The line y=xy = x intersects CC. Find the exact xx-coordinates of the points of intersection. (4 marks)
    (d) State the number of points of intersection of CC with the line y=xy = x. (1 mark)
    Level 4 · 9 marksTry it

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