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    \frac{dy}{dx} = \frac{x^2 - y^2}{y} using the substitution  y = \sqrt z

    Firstly I change dy/dx into dz/dx using the chain rule:

    dy/dx = dy/dz . dz/dx ... dy/dz = 1/2
    \frac {dy}{dx} = \frac {1}{2} . \frac {dz}{dx}

    Then I sub into the initial equation and:

    \frac {dz}{dx} = \frac {2x^2}{\sqrt z} - 2\sqrt z

    I don't know where to go from here, help would be appreciated.
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    How did you get \frac{dy}{dz}=\frac{1}{2} ?
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    I'm an idiot.

    Ignore this thread ... thanks for spotting that notnek.
 
 
 
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Updated: January 28, 2010
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