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Math Help - Change in y and differentrial dy

  1. #1
    Member mybrohshi5's Avatar
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    Change in y and differentrial dy

    Let .
    Find the change in , when and
    Find the differential when and

    can i get some help with this please?

    thank you
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  2. #2
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    Quote Originally Posted by mybrohshi5 View Post
    Let .
    Find the change in , when and
    Find the differential when and

    can i get some help with this please?

    thank you
    Currently,  y = f(x)

    So we can say that  y + \Delta y = f(x+ \Delta x)

    We can then re-write this as:  \Delta y = f(x+\Delta x) - y

    And we know that  y = f(x) , so we can say:

     \Delta y = f(x+\Delta x) - f(x)

    We know that  f(x) = 4 \sqrt{x}

    So:

     \Delta y = 4 \sqrt{x + \Delta x} - 4 \sqrt{x}

    For the second part, just differentiate it and then take it from there.
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  3. #3
    Member
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    for the first one use the formula;
    = f(x+delta(x))-f(x)
    and for the other
    dy=f'(x)dx
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