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Math Help - Find the differential of a function

  1. #1
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    Find the differential of a function

    Find the differential of :



    Find dy.

    I'm not sure what the 'differential' means, or how to find dy.

    Thanks.
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by TSizzle55 View Post
    Find the differential of :



    Find dy.

    I'm not sure what the 'differential' means, or how to find dy.

    Thanks.
    why didn't you look it up in your text?

    the differential dy is given by:

    dy = f'(x) ~dx
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  3. #3
    Rhymes with Orange Chris L T521's Avatar
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    Quote Originally Posted by TSizzle55 View Post
    Find the differential of :



    Find dy.

    I'm not sure what the 'differential' means, or how to find dy.

    Thanks.
    A differential is defined as \,dy=f'(x)\,dx

    In essence, you find \frac{\,dy}{\,dx}=f'(x), and then multiply both sides by \,dx to get the equation I defined above.

    Can you try to do the problem now?

    --Chris
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    A differential is defined as

    In essence, you find , and then multiply both sides by to get the equation I defined above.

    Can you try to do the problem now?


    Yes, I get dy = x(3xcos(3x) + 2sin(3x)) dx

    But how do I find dx? In other words, I need dy without dx anywhere in the equation. Is it possible to substitute something in for dx?
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  5. #5
    Rhymes with Orange Chris L T521's Avatar
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    Quote Originally Posted by TSizzle55 View Post
    A differential is defined as

    In essence, you find , and then multiply both sides by to get the equation I defined above.

    Can you try to do the problem now?


    Yes, I get dy = x(3xcos(3x) + 2sin(3x)) dx

    But how do I find dx? In other words, I need dy without dx anywhere in the equation. Is it possible to substitute something in for dx?
    Yes, its possible. They usually give the value of \,dx in the problem.

    --Chris
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