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Thread: Domain

  1. #1
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    Domain

    find the domain of -4sin(3x)
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  2. #2
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    sin(x) is defined for all real numbers, so are sin(3x) and -4sin(3x)
    Last edited by papex; May 28th 2010 at 08:14 PM.
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  3. #3
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    Quote Originally Posted by papex View Post
    sin(x) is defined for all real numbers, so are sin(3x) and -4sinsin(3x)
    I want to find the domain of -4 sin (3x).
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  4. #4
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    Hello winsome

    Do you understand what is meant by the word domain of a function? It is the set of valid inputs to that function. For example, the domain of $\displaystyle \sqrt x$ is the set of non-negative numbers.

    Now, as papex has said, $\displaystyle \sin x$, and therefore $\displaystyle \sin3x$ and $\displaystyle -4\sin 3x$, are defined for all values of $\displaystyle x$. In other words, the domain of these functions is the set of all real numbers.

    There are various ways of writing this set. One is to use the symbol $\displaystyle \mathbb{R}$. Another is to use interval notation: $\displaystyle (-\infty, +\infty)$.

    Grandad
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