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2.14 Odd and even functions; inverse with domain restrictionIB Maths: Analysis and Approaches HL: Subtopic test

10 questions, 27 marks

IB Maths: Analysis and Approaches HL

2.14 Odd and even functions; inverse with domain restriction

Total 27 marks

Name

Class

Date

  1. 1
    The functions ff, gg and hh are defined for x∈Rx\in\mathbb{R} by f(x)=x3−4xf(x)=x^{3}-4x, g(x)=x4+2cos⁡xg(x)=x^{4}+2\cos x and h(x)=x2+xh(x)=x^{2}+x.
    (a)
    Which of the functions ff, gg and hh are even?
    [1 mark]
    • Agg only
    • Bff only
    • Cff and gg
    • Dgg and hh
    (b)
    The function pp is defined by p(x)=f(x) g(x)p(x)=f(x)\,g(x). Which statement about pp is true?
    [1 mark]
    • App is even
    • Bpp is both odd and even
    • Cpp is odd
    • Dpp is neither odd nor even
    (c)
    The function qq is defined by q(x)=f(x)+bx2+cx+dq(x)=f(x)+bx^{2}+cx+d, where b,c,d∈Rb,c,d\in\mathbb{R}. Given that qq is an odd function, find the value of bb and the value of dd.
    [2 marks]

    Total for question 1: 4 marks

  2. 2
    The function kk is defined for x∈Rx\in\mathbb{R} by k(x)=sin⁡2x+xcos⁡xk(x)=\sin 2x+x\cos x.
    (a)
    Which statement about kk is true?
    [1 mark]
    • Akk is even
    • Bkk is neither odd nor even
    • Ckk is both odd and even
    • Dkk is odd
    (b)
    Find k(−π4)k\left(-\frac{\pi}{4}\right).
    [1 mark]
    • A1+π281+\frac{\pi\sqrt{2}}{8}
    • B−1−π28-1-\frac{\pi\sqrt{2}}{8}
    • C−1+π28-1+\frac{\pi\sqrt{2}}{8}
    • D1−π281-\frac{\pi\sqrt{2}}{8}
    (c)
    Given that k(a)=5k(a)=5 for some real number aa, find the value of k(a)+k(−a)+k(0)k(a)+k(-a)+k(0). Justify your answer.
    [2 marks]

    Total for question 2: 4 marks

  3. 3
    The height, in metres, of a stone above the ground tt seconds after it is thrown upwards from the top of a cliff is modelled by h(t)=11+6t−t2h(t)=11+6t-t^{2}, for 0≤t≤T0\le t\le T, where TT is the time at which the stone hits the ground.
    (a)
    Express h(t)h(t) in the form p−(t−q)2p-(t-q)^{2}, and hence explain why hh does not have an inverse function on the domain 0≤t≤T0\le t\le T.
    [3 marks]
    (b)
    The function gg is the restriction of hh to the domain 3≤t≤T3\le t\le T. Find g−1(x)g^{-1}(x), stating its domain, and hence find the time at which the falling stone is 1111 m above the ground.
    [4 marks]

    Total for question 3: 7 marks

  4. 4
    The function gg is defined by g(x)=3x+5x−3g(x)=\dfrac{3x+5}{x-3}, for x∈Rx\in\mathbb{R}, x≠3x\neq3. The function rr is defined by r(x)=px+72x+qr(x)=\dfrac{px+7}{2x+q}, for x≠−q2x\neq-\frac{q}{2}, where p,q∈Rp,q\in\mathbb{R}.
    (a)
    (i) Show that (g∘g)(x)=x(g\circ g)(x)=x.\n(ii) Hence write down g−1(x)g^{-1}(x), and state the domain and the range of g−1g^{-1}.
    [6 marks]
    (b)
    Find an expression for r−1(x)r^{-1}(x) in terms of pp and qq. Hence find qq in terms of pp for which rr is self-inverse, and write down r(x)r(x) in this case when p=4p=4.
    [6 marks]

    Total for question 4: 12 marks

End of questions