microeconomics
posted by Dave .
Ok, if anyone is able to help me within the next 12 hours or so, that would be wonderful! I think I am going about this problem correctly  I am not looking for someone to solve this problem for me, but for someone to tell me if I am doing it right...
You can see this chapter, and the question, by going to google and typing in "consider a linear demand curve, Q" (with the quotations), then choosing the last result (the PDF).
That is a .pdf version of the chapter. I am working on question 2.9, part C (this is the second to last page of the .pdf)
The question says "Consider a linear demand curve, Q = 350  7P. What is the price elasticity of demand at P = 50?
Using an equation in that chapter, (b)(P/Q), I end up with the equation:
7 ( 50 / (350  7(50)) )
But the problem is that 350  7(50) is 0! That means that the division can't be done, because the denominator is 0! So does this mean that the price elasticity of demand at P = 50 does not exist? How is this possible?
Thanks in advance! Dave
It's been some time since I had microecon, so I'm quite reluctant to speak like an expert on the subject. The math involved doesn't look exceptionally difficult, but I don't recall what the terms and symbols stand for.
I can comment on your observation/question, "...the denominator is 0! So does this mean that the price elasticity of demand at P = 50 does not exist? How is this possible? " though.
If you're calculations are correct, then the change in x is 0. This means you have a vertical asymptote at that point. I'm unsure how that should be interpreted though. You might want to study how the curve behaves in a very small neighborhood of the point P=50 to see how the curve is behaving there.
Does that help?
The short answer: the POINT elasticity at P=50 is infinite.

we also have the same problem...