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DP IB Maths: AA HL

Topic Questions

Home / IB / Maths: AA HL / DP / Topic Questions / 2. Functions / 2.5 Reciprocal & Rational Functions


2.5 Reciprocal & Rational Functions

Question 1a

Marks: 1

Let f open parentheses x close parentheses equals fraction numerator b over denominator x minus a end fraction plus 2, for x not equal to a.

The line x equals negative 3 is a vertical asymptote of the graph of f.

(a)
Write down the value of a.

 

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    Question 1b

    Marks: 3

    The graph of f passes through the point straight A open parentheses 4 comma negative 2 close parentheses.

    (b)
    Find the value of b.
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      Key Concepts
      Graphing Functions

      Question 1c

      Marks: 2
      (c)
      Find limit as x rightwards arrow infinity of f open parentheses x close parentheses.
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        Question 2a

        Marks: 6

        Consider f open parentheses x close parentheses equals fraction numerator a x plus b over denominator c x plus 1 end fraction, where a comma space b comma space c element of straight integer numbers.

        y equals 4 and  x equals negative 1 are the equations of the asymptotes of the graph of f. Point straight P open parentheses 5 comma 9 over 2 close parentheses lies on the graph.

        (a)
        Find the values of a comma space b and c.
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          Question 2b

          Marks: 4
          (b)
          Sketch the graph of y equals f open parentheses x close parentheses.
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            Question 3a

            Marks: 1

            Let f open parentheses x close parentheses equals fraction numerator 3 over denominator x minus a end fraction plus b, for x not equal to a. 

            The line x equals 2 is a vertical asymptote of the graph of f

            (a)
            Write down the value of a.

             

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              Question 3b

              Marks: 3

              The graph of f passes through the point straight A open parentheses 1 comma 5 close parentheses.

              (b)
              Find the value of b.
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                Key Concepts
                Key Features of Graphs

                Question 3c

                Marks: 2
                (c)
                Find limit as x rightwards arrow infinity of f open parentheses x close parentheses.
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                  Question 4a

                  Marks: 2

                  Consider the function f defined by f open parentheses x close parentheses equals fraction numerator 3 x minus 7 over denominator x squared minus 6 x plus 5 end fraction, for x not equal to 1.5.

                  (a)
                  Find the coordinates where the graph of f intersects the coordinate axes.
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                    Question 4b

                    Marks: 3
                    (b)
                    (i)
                    Express f open parentheses x close parentheses as partial fractions.
                    (ii)
                    Hence, write down the equation of the horizontal asymptote.
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                      Key Concepts
                      Partial Fractions

                      Question 4c

                      Marks: 4
                      (c)
                      Sketch the graph of y equals f open parentheses x close parentheses.
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                        Question 5a

                        Marks: 6

                        The graph of a function f is shown below. The equations of the asymptotes are x equals 0.25 and y equals 0.5. The graph crosses the coordinate axes at the points straight A left parenthesis 0 comma space m right parenthesis and straight B left parenthesis 5 comma 0 right parenthesis.

                        q5a-2-5-ib-aa-hl-reciprocal-_-rational-functions-hard-maths-diagram

                        (a)
                        Find an equation for f open parentheses x close parentheses in the form  fraction numerator a x plus b over denominator c x plus d end fraction, where a comma space b comma space c comma space d element of straight integer numbers.
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                          Question 5b

                          Marks: 1
                          (b)
                          Write down the value of m.
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                            Question 6a

                            Marks: 3

                            Consider the function f open parentheses x close parentheses equals fraction numerator 2 x squared minus x minus 15 over denominator x minus 2 end fraction comma space x element of straight real numbers comma space x not equal to 2.

                            (a)
                            Find the coordinates where the graph of f crosses the
                            (i)
                            x-axis,
                            (ii)
                            y-axis.
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                              Question 6b

                              Marks: 4
                              (b)
                              Find the equation of the oblique asymptote of the graph of f, giving the answer in the form y equals a x plus b where a comma b element of straight integer numbers..
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                                Question 6c

                                Marks: 4
                                (c)
                                Sketch the graph of y equals f open parentheses x close parentheses. Clearly indicate the asymptotes and give coordinates of the points where the graph intersects the axes.
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                                  Question 7

                                  Marks: 6

                                  Consider the function f defined by f open parentheses x close parentheses equals fraction numerator a x plus b over denominator 2 x squared plus c x plus d end fraction comma where a comma space b comma space c comma space d element of straight integer numbers. The lines x equals negative 1 half and x equals 3 are vertical asymptotes of the graph of f as shown below. The graph crosses through the points straight A open parentheses 0 comma 4 close parentheses and straight B open parentheses 2 comma 0 close parentheses.

                                  q7-2-5-ib-aa-hl-reciprocal-_-rational-functions-hard-maths-diagram

                                  Find the values of a comma space b comma space c and d.

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                                    Question 8a

                                    Marks: 2

                                    The graph of a function f is shown below. The equations of the asymptotes are x equals 3 and y equals 3 x minus 2. The graph crosses the y-axis at open parentheses 0 comma space minus 2.5 close parentheses.

                                    q8a-2-5-ib-aa-hl-reciprocal-_-rational-functions-hard-maths-diagram

                                    The function can be written as f open parentheses x close parentheses equals a x plus b plus fraction numerator 3 over denominator c x plus d end fraction, where a comma space b comma space c comma space d space element of straight integer numbers. 

                                    (a)
                                    Find the values of a comma space b comma space c and d.
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                                      Question 8b

                                      Marks: 3
                                      (b)
                                      Find the exact coordinates of the points where y equals f open parentheses x close parentheses crosses the x-axis.
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                                        Question 8c

                                        Marks: 2
                                        (c)
                                        Given that f open parentheses x close parentheses equals k has no real solutions where k element of straight real numbers, find the set of possible values of k. Give the bounds correct to 2 decimal places.
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                                          Key Concepts
                                          Intersecting Graphs

                                          Question 9a

                                          Marks: 4

                                          Consider the function f open parentheses x close parentheses equals fraction numerator 2 x squared minus 18 over denominator x squared minus 25 end fraction, for x not equal to plus-or-minus 5.

                                          (a)
                                          (i)
                                          Show that fraction numerator 2 x squared minus 18 over denominator x squared minus 25 end fraction equals 2 plus fraction numerator 16 over denominator 5 open parentheses x minus 5 close parentheses end fraction minus fraction numerator 16 over denominator 5 open parentheses x plus 5 close parentheses end fraction.
                                          (ii)
                                          Hence, write down the value of limit as x rightwards arrow infinity of f open parentheses x close parentheses.
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                                            Question 9b

                                            Marks: 4
                                            (b)
                                            (i)
                                            Sketch the graph of y equals f open parentheses x close parentheses.
                                            (ii)
                                            Write down the range of f.
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                                              Key Concepts
                                              Graphing Functions

                                              Question 10a

                                              Marks: 2

                                              Consider the function f open parentheses x close parentheses equals fraction numerator 2 x squared minus 72 over denominator x squared minus 9 end fraction, for x not equal to plus-or-minus 3

                                              (a)
                                              Prove that f is an even function.

                                               

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                                                Key Concepts
                                                Odd & Even Functions

                                                Question 10b

                                                Marks: 5
                                                (b)
                                                (i)
                                                Sketch the graph of y equals f open parentheses x close parentheses.
                                                (ii)
                                                Write down the range of f.

                                                 

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