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    Can someone explain what this really is about because from what I have learnt in 2 hours is that u just manipulate the variables to find the rate of something that is increasing or decreasing but I don't get what the point is .

    Name:  1483747035629-1937288554.jpg
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Size:  364.8 KB for this question I don't get how the answer is just -kM . Why wouldn't you do something like this Attachment 609096609098

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    dm/dt is proportional to -M, the minus there as it is a rate of decrease, so it is equal to some multiple of M.

    dm/dt = -kM
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    You're overcomplicating it. All this question is asking you to do is to express the problem described in the question using an equation. The question says that the rate of loss of mass of the leaf is proportional to the mass of the leaf. The rate of change of mass of the leaf is \frac{dM}{dt} and since this is proportional to the mass of the leaf, \frac{dM}{dt}=kM. However, since we are talking about the rate of loss of mass of the leaf, the rate of change of the mass of the leaf is negative. So \frac{dM}{dt}=-kM (assuming k>0).
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    (Original post by coconut64)
    Attachment 609096609098

    Thanks
    It's not clear what you're trying to show in this image. Can you please explain it line by line?
 
 
 
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