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Math Help - differentiation

  1. #1
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    differentiation

    given that f(x,y) =(x^3 +y^3) ^(1/3). determine whether fy(0,0) exist?


    my working:

    i differentiated wrt to y, and then sub in (0,0) and i got that fy=0.

    but my answer says that fy exists...
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  2. #2
    Senior Member AllanCuz's Avatar
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    Quote Originally Posted by alexandrabel90 View Post
    given that f(x,y) =(x^3 +y^3) ^(1/3). determine whether fy(0,0) exist?


    my working:

    i differentiated wrt to y, and then sub in (0,0) and i got that fy=0.

    but my answer says that fy exists...
    If a derivative exists what does that mean? Can a derivative exist and have a value of 0?

    Well, what is a derivative? A derivative will tell us the slope of the tangent to the curve at a given point. Let me ask you this, can we have a horizontal tangent to the curve (i.e. no slope) and if we can, does this still "exist"?
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