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  • Perplex
    IB Math AAHL
    /
    Exponents & Logarithms
    /

    Exponential Algebra

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    Exercises

    Key Skills

    Exponential Algebra

    Exponential Algebra

    Exponents, properties of exponents, and solving exponential equations

    Want a deeper conceptual understanding? Try our interactive lesson!

    Exercises

    No exercises available for this concept.

    Practice exam-style exponential algebra problems

    Key Skills

    Exponential Notation
    SL Core 1.5

    Exponential expressions are a shortcut for writing the multiplication of a number by itself many times:

    ​
    an=a×a×⋯×a​n times​🚫
    ​

    Here ​a​ is called the base and ​n​ the exponent. We say that ​a​ is raised to the ​nth​ power.


    Note that ​a1=a, since we have ​1×a=a.

    Exponent with zero
    SL Core 1.5

    Any number raised to the power zero is

    ​
    a0=1×a×a×⋯×a​0 times​=1🚫
    ​

    And since any number multiplied by ​0​ is ​0:

    ​
    0n=0,n=0🚫
    ​

    When ​n=0, we have ​00, which is technically undefined, but in most contexts is defined to be

    ​
    00=1🚫
    ​
    Multiplying powers with the same base
    SL Core 1.5

    When multiplying exponentials with the same base, the following rule applies:


    ​
    an⋅am    ​=a×a×⋯×a​n times​×a×a×⋯×a​m times​ =a×a×⋯×a​n+m times​ =am+n🚫​
    ​
    Exponential of exponential
    SL Core 1.5

    An exponential can be the base of another exponential:

    ​
    (am)n=a×⋯×a​m times​×⋯×a×⋯×a​m times​​n times​=anm🚫
    ​
    Negative exponents
    SL Core 1.5
    ​
    a−n=an1​,a=0🚫
    ​
    Dividing exponents with the same base
    SL Core 1.5

    In general,

    ​
    aman​=an⋅a−m=an−m,a=0🚫
    ​
    Exponents of products & quotients
    SL Core 1.5

    When exponentials with the same power are being multiplied or divided, the bases can be combined:

    ​
    anbn=(ab)n🚫
    ​
    ​
    bnan​=(ba​)n,b=0🚫
    ​
    Exponential Equations (Equating Indices)
    SL AA 1.7

    If two exponentials in the same positive base are equal, their exponents must be equal:

    ​
    an=am⇔n=m,a>0,a=1🚫
    ​


    Exponentials can also appear in equations with one or more unknown:

    ​
    (21​)x−1=8x+1
    ​
    ​
    ⇒(2−1)x−1=(23)x+1
    ​
    ​
    ⇒21−x=23x+3
    ​

    Now we can equate the exponents:

    ​
    1−x=3x+3⇒x=−21​
    ​