Saturday

December 20, 2014

December 20, 2014

Posted by **Arc Length** on Sunday, August 24, 2008 at 9:11pm.

y = (1/8)(4x^2-2ln(x)) from x=4 to x=8.

I found the derivative of the function and got y'= x-(1/4x)

Where I'm lost now is after plugging it into the arc length equation: integral of sqrt(1+(x-(1/4x))^2). Squaring the derivative yields me sqrt(1+x^2+1/16x-1/2). Help please.

- calculus -
**Damon**, Sunday, August 24, 2008 at 9:47pmI got sqrt [ 1 + x^2 -(1/2) + 1/(16x^2) ]

which is

sqrt [ x^2 + (1/2) +1/(16x^2) ]

BUT

x^2 + (1/2) + 1/(16x^2) = [x+ 1/(4x)]^2

ok ?

- calculus -
**Arc Length**, Sunday, August 24, 2008 at 10:12pmOh yes, sorry, I merely had a typo. I had the same result as you. What I'm confused about is what to do from that point on.

- calculus -
**Damon**, Monday, August 25, 2008 at 3:50amwell, the sqrt of that is just

x + (1/4)(1/x)

integral of that is

(1/2) x^2 + (1/4) ln x

**Answer this Question**

**Related Questions**

Calculus - I know how to do this problem, but I'm stuck at the arc length ...

Calculus - Evaluate (integral) cot 2x dx. A. 1/2Ln sin 2x+C B. 1/2Ln cos 2x+C C...

Calculus - Given the function: f(x) = x^2 + 1 / x^2 - 9 a)find y and x ...

Calculus - Find the extreme value(s) of the function f(x)=1/(1-x^2). I tried, ...

Calculus - Given the function: f(x) = x^2 + 1 / x^2 - 9 a)find y and x ...

Calculus - Given the function: f(x) = x^2 + 1 / x^2 - 9 a)find y and x ...

Applied Calculus - Find the first and second derivative of the function: x/(7x+...

calculus - find the derivative of the function (6x+1)/(19x+1)^1/2 PLEASE EXPLAIN...

Calculus again - Find the equation of the tangent to y=2-xe^x at the point where...

CALCULUS 2!!! PLEASE HELP!! - I'm having trouble with this question on arc ...