Find the area of the region, R, bounded by the curve y=x^(-2/3), the line x = 1 and the x axis . In addition, find the volume of revolution of this region when rotated 2 pi radians around the x axis.

As we are looking to find the area under a curve we can use integration. The area under a curve with equation y = f(x), bounded by the lines x = a and x = b and the x axis can be expressed as:A = integral (from a to b) f(x) dxThus, the area of the region, R, can be expressed as:R = integral (from 1 to infinity) x^(-2/3) dxR = [3x^(1/3)] (from 1 to infinity)R = (3infinity(1/3))-(31^(1/3)) = infinity - 3 = infinityR = infinityTherefore the region has infinite area, Considering now the volume of revolution, again using integration:The volume of revolution 2pi radians around the x axis of the same region described above can be expressed:V = pi * integral (from a to b) f(x)^2 dxThus, for the curve in question:V = pi * integral (from 1 to infinity) [x^(-2/3)]^2 dx = pi * integral (from 1 to infinity) x^(4/3) dxV = [-3x^(-1/3)] (from 1 to infinity) = (-3infinity^(-1/3))-(-31^(-1/3)) = 0 - (-3) = 3V = 3This interesting problem shows that a region can have infinity area but its revolution can have fininte volume 

Answered by Henri F. Maths tutor

7593 Views

See similar Maths A Level tutors

Related Maths A Level answers

All answers ▸

I'm supposed to calculate the differential of f(x)= sin(x)*ln(x)*(x-4)^2 using the product rule. I know what the product rule is but I can't split this into two bits that are easy to differentiate. How do I do it?


A sequence is defined as: U(n+1) = 1/U(n) where U(1)=2/3. Find the sum from r=(1-100) for U(r)


How do I differentiate (2x+1) / (3x^2 - 5)?


Express (16x^2 + 4x^3)/(x^3 + 2x^2 - 8x) + 12x/(x-2) as one fraction in its simplest form.


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2024

Terms & Conditions|Privacy Policy
Cookie Preferences