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    hey would anyone be able to help me

    i have to differentiate cos(xy)=0.5

    i typed my equation in and got a differentiative of 0=-ysinxy-xsinxydy/dx which gives me the right answer but i dont know how to get to it

    thanks xxx
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    (Original post by mickymouse1995)
    hey would anyone be able to help me

    i have to differentiate cos(xy)=0.5

    i typed my equation in and got a differentiative of 0=-ysinxy-xsinxydy/dx which gives me the right answer but i dont know how to get to it

    thanks xxx
    This is a combination of chain rule, product rule and implicit differentiation.
    Differentiate cos(STUFF) then multiply by the derivative of the stuff in the brackets.
    Hint: d/dx(y) = dy/dx
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    Chain rule:

    [cos(xy)]' = cos'(xy) * [xy]'

    As for [xy]', product rule:

    [xy]' = x'y + y'x
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    thank you i understand now xx
 
 
 
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