Re: Arc Length

On Apr 17, 10:25 am, Dave <dave_and_da...@xxxxxxxx> wrote:
On Apr 16, 6:31 pm, kaig...@xxxxxxxxx wrote:

I'm trying to find the arclength of y = (1/2)x^2 - (1/4)ln(x) from x=2
to x=5 but am having some trouble. Here's what I've done so far:

y' = x - (1/4x) = (4x^2 - 1)/4x

arclength = s = integral((1 + ((4x^2 - 1)/4x)^2)^(1/2)) with respect
to x from x=2 to x=5.

But I don't know how to solve this integral.

Any help much appreciated!

Simplify the integrand and you'll find that the quantity you need to
take the square root of is a perfect square, so the integral becomes
you that you should be able to do.

Dave

Thanks for your help. Unfortunately, I get the integrand is ((16x^4 -
4x^2 + 1)/4x)^(1/2), which doesn't seem to reduce to a perfect square.
Any pointers? Have I made a mistake?
.

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