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Find the value of the second derivative at a point, given the first derivative Watch

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    If the first derivative = 2xy, then the value of the second derivative at the point (1,2) is?
    a) 6
    b) 8
    c) 12
    d) 16

    I'm stumped, i don't know how to even start a question like this. Its new to me.
    Can someone help me with this question? or at least give me some steps to follow?
    Thanks
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    (Original post by ksrw395)
    If the first derivative = 2xy, then the value of the second derivative at the point (1,2) is?
    a) 6
    b) 8
    c) 12
    d) 16

    I'm stumped, i don't know how to even start a question like this. Its new to me.
    Can someone help me with this question? or at least give me some steps to follow?
    Thanks
    You have f ' (x) = 2xy

    Differentiate both sides with respect to x to get
    f '' (x) = 2x(dy/dx) + 2y

    Using the product rule. Now plug in the co-ords to get the gradient.
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    (Original post by Zacken)
    You have f ' (x) = 2xy

    Differentiate both sides with respect to x to get
    f '' (x) = 2x(dy/dx) + 2y

    Using the product rule. Now plug in the co-ords to get the gradient.
    I did that and i got 12.
    Thanks
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    (Original post by ksrw395)
    I did that and i got 12.
    Thanks
    No problem.
 
 
 
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