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# fp1 parabolas watch

1. 8) The point P lies on the rectangular hyperbola xy = c^2, where c > 0. The tangent to the rectangular hyperbola at the point P(ct, c/t), t > 0, cuts the x axis at the point X and cuts the y-axis at the point Y.

(a) Find in terms of c and t, the coordinates of X and Y

y = c^2 /x
dy/dx = - c^2/x^2
dy/dx = - c^2 / c^2 t^2
dy/dx = - 1 / t^2

y - c/t = -1/t^2 (x-ct)
yt - c = - x/t + c
yt^2 - ct = -x + c

apparently this is wrong... go on...
2. You should have on the RHS of the last line.
3. Now that nuodai has pointed it out, we can all see it, so this is going to be very expensive; seeing as you didn't restrict your offer to the first one!
4. Did he pay lol??
5. (Original post by cheeseandbiscuits)
Did he pay lol??
Nope (nor did I expect him to), but a mod removed all the money stuff... for obvious reasons.

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Updated: October 1, 2010
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