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2.6 The quadratic functionIB Maths: Analysis and Approaches SL: Subtopic test

10 questions, 27 marks

IB Maths: Analysis and Approaches SL

2.6 The quadratic function

Total 27 marks

Name

Class

Date

  1. 1
    The function ff is defined by f(x)=2x2−12x+10f(x) = 2x^2 - 12x + 10, for x∈Rx \in \mathbb{R}.
    (a)
    Find the equation of the axis of symmetry of the graph of y=f(x)y = f(x).
    [1 mark]
    • Ax=3x = 3
    • Bx=−3x = -3
    • Cx=6x = 6
    • Dx=5x = 5
    (b)
    Which expression is f(x)f(x) written in the form a(x−h)2+ka(x - h)^2 + k?
    [1 mark]
    • A2(x−3)2+12(x - 3)^2 + 1
    • B2(x+3)2−82(x + 3)^2 - 8
    • C2(x−3)2+282(x - 3)^2 + 28
    • D2(x−3)2−82(x - 3)^2 - 8
    (c)
    Write f(x)f(x) in the form 2(x−p)(x−q)2(x - p)(x - q), and hence write down the xx-intercepts of the graph of y=f(x)y = f(x).
    [2 marks]

    Total for question 1: 4 marks

  2. 2
    The function gg is defined by g(x)=−3(x+2)2+12g(x) = -3(x + 2)^2 + 12, for x∈Rx \in \mathbb{R}.
    (a)
    Write down the coordinates of the vertex of the graph of y=g(x)y = g(x).
    [1 mark]
    • A(2,12)(2, 12)
    • B(−2,12)(-2, 12)
    • C(−2,−12)(-2, -12)
    • D(2,−12)(2, -12)
    (b)
    Find the yy-intercept of the graph of y=g(x)y = g(x).
    [1 mark]
    • A(0,24)(0, 24)
    • B(0,12)(0, 12)
    • C(0,0)(0, 0)
    • D(0,6)(0, 6)
    (c)
    Write g(x)g(x) in the form −3(x−p)(x−q)-3(x - p)(x - q).
    [2 marks]

    Total for question 2: 4 marks

  3. 3
    A footbridge is supported by an arch in the shape of a parabola. The height of the arch above the ground is h(x)h(x) metres at a horizontal distance of xx metres from one foot of the arch. The arch meets the ground at x=0x = 0 and at x=40x = 40, and its maximum height is 12 m.
    (a)
    Show that h(x)=−0.03x(x−40)h(x) = -0.03x(x - 40).
    [3 marks]
    (b)
    A vehicle 8 m wide and 11 m high drives along the ground under the arch, keeping its centre directly below the highest point of the arch. Determine whether the vehicle can pass under the arch. Justify your answer.
    [4 marks]

    Total for question 3: 7 marks

  4. 4
    The quadratic function ff can be written in the form f(x)=a(x+1)2+18f(x) = a(x + 1)^2 + 18. The graph of y=f(x)y = f(x) passes through the point (2,0)(2, 0). A second quadratic function gg has the same zeros as ff, and the graph of y=g(x)y = g(x) passes through the point (0,24)(0, 24).
    (a)
    (i) Find the value of aa.
    (ii) Show that
    f(x)=−2x2−4x+16f(x) = -2x^2 - 4x + 16.
    (iii) Write
    f(x)f(x) in the form a(x−p)(x−q)a(x - p)(x - q).
    [6 marks]
    (b)
    (i) Find g(x)g(x) in the form b(x−p)(x−q)b(x - p)(x - q).
    (ii) Show that
    g(x)=1.5f(x)g(x) = 1.5f(x) for all values of xx.
    (iii) Write down the coordinates of the vertex of the graph of
    y=g(x)y = g(x), and explain why the graphs of ff and gg have the same axis of symmetry.
    [6 marks]

    Total for question 4: 12 marks

End of questions