Is P Inversely Proportional to R Squared?

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P is proportional to q², and q is inversely proportional to r, leading to the conclusion that p is inversely proportional to r². The relationship can be expressed mathematically as p = k(c/r)², simplifying to p = (kc²)/r². This indicates that as r increases, p decreases, confirming the inverse relationship. The initial assumption that p could be proportional to r² is incorrect based on the given equations. Therefore, p is indeed inversely proportional to r².
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Homework Statement


If P is proportional to q^2
and q is inversely proportional to r

Show that p is proportional to r^2


Homework Equations


p = kq^2
q = c/r

where k and c are proportional constants


The Attempt at a Solution



I'd say this is impossible. This is all the information given to me. This was found in an exam paper.

But even if we assume

k = c

p is not proportional to r^2.

-.-

Any ideas?
 
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You might have read the question wrong. If p ∝ q², and q ∝ 1/r, then p ∝ 1/r².
 
p=kq^2
q=c/r
therefore
p=k(c/r)^2
or
p=(kc^2)/r^2

So p should be inversely proportional to r^2, with the constant of kc^2.
 
Since ##px^9+q## is the factor, then ##x^9=\frac{-q}{p}## will be one of the roots. Let ##f(x)=27x^{18}+bx^9+70##, then: $$27\left(\frac{-q}{p}\right)^2+b\left(\frac{-q}{p}\right)+70=0$$ $$b=27 \frac{q}{p}+70 \frac{p}{q}$$ $$b=\frac{27q^2+70p^2}{pq}$$ From this expression, it looks like there is no greatest value of ##b## because increasing the value of ##p## and ##q## will also increase the value of ##b##. How to find the greatest value of ##b##? Thanks
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