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  • Perplex
    IB Math AIHL
    /
    Modelling
    /

    Power Models & Proportionality

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    Exercises

    Key Skills

    Power Models & Proportionality

    Power Models & Proportionality

    Modeling with functions of the form ​axn, and the concept of direct and inverse variation

    Want a deeper conceptual understanding? Try our interactive lesson!

    Exercises

    No exercises available for this concept.

    Practice exam-style power models & proportionality problems

    Key Skills

    Direct Proportion
    SL AI 2.5

    Directly proportional quantities are constant multiples of each other. In the context of modelling, we typically say, "​y​ varies directly with ​xn," which means ​y=kxn​ for some constant ​k. This can be denoted ​y∝xn.


    If ​y​ is directly proportional to ​xn, then ​x=0⟺y=0.


    If ​y​ is directly proportional to ​xn, then if ​x​ increases (or decreases) by a factor of ​c, ​y​ increases (or decreases) by a factor of ​cn.

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    Inverse proportion
    SL AI 2.5

    If ​y​ varies inversely with ​xn, then ​y=xnk​.


    If ​y​ is inversely proportional to ​xn​ ​(y∝xn1​), then the ​y​-axis is an asymptote of the graph of ​y=f(x).

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