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# Simple c4 question =/ watch

1. Oks

A curve c has equation y=f(x), y>0. At any point P on the curve, the gradient of C is proportional to the product of the x and y coordinates of P. The point A with coordinates (4,2) Is on C and the gradient of C at A is 1/2.

Show that dy/dx = xy/16

Im realy unsure on the wording of the question and how to auctaly answer it >.< Any help please?
2. the gradient is proportional to the product of the x and y coordinates

i.e. dy/dx = kxy

plug in the values you have

1/2 = 8k
k = 1/16

now you have k, substitute it back into dy/dx = kxy

dy/dx = xy/16

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Updated: February 8, 2010
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