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    Find the point or points on the curve with equation y=f(x) where the gradient is zero: f(x) x^-1+4x
    I have done this up until -x^-2=4 and then I have no clue what to do from here any help would be appreciated
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    (Original post by Sukjeetsandhu)
    Find the point or points on the curve with equation y=f(x) where the gradient is zero: f(x) x^-1+4x
    I have done this up until -x^-2=4 and then I have no clue what to do from here any help would be appreciated
    The gradient is 0 when  f'(x)=0

    since f'(x) is the gradient function after all
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    Moved to maths.
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    (Original post by Sukjeetsandhu)
    Find the point or points on the curve with equation y=f(x) where the gradient is zero: f(x) x^-1+4x
    I have done this up until -x^-2=4 and then I have no clue what to do from here any help would be appreciated
    It should be -x^{-2}=-4 or x^{-2}=4, not what you wrote. Let me know if you can't see why.

    At this point you can change back into fraction form :

    \displaystyle x^{-2}=4\Rightarrow \frac{1}{x^2} = 4

    Can you carry on from here?
 
 
 
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Updated: January 14, 2017
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