Got Homework?
Connect with other students for help. It's a free community.
Here's the question you clicked on:
 0 viewing
pdd21
Group Title
Calc Problem: Help please!
Find the volume of the solid obtained by rotating the region bounded by y=9 x^2, x = 1, and y = 0, about the xaxis.
 7 months ago
 7 months ago
pdd21 Group Title
Calc Problem: Help please! Find the volume of the solid obtained by rotating the region bounded by y=9 x^2, x = 1, and y = 0, about the xaxis.
 7 months ago
 7 months ago

This Question is Closed

pdd21 Group TitleBest ResponseYou've already chosen the best response.0
@campbell_st
 7 months ago

campbell_st Group TitleBest ResponseYou've already chosen the best response.1
ok the the formula for rotating about the x axis is \[V = \pi \int\limits_{a}^{b} y^2 dx\] so the values of a and b are and then y = 0 the corresponding value of x is x = 0... so that means a = 0 and b = 1 the graph looks like dw:1386823443784:dw so you are looking at \[V = \pi \int\limits_{0}^{1} (9x^2)^2 dx\] so just simply the (9x^2)^2 then integrate and evaluate between x = 1 and x = 0
 7 months ago

campbell_st Group TitleBest ResponseYou've already chosen the best response.1
hope this helps
 7 months ago

pdd21 Group TitleBest ResponseYou've already chosen the best response.0
Thank you so much that helped clear up my confusion! there was another problem I was stuck on, but instead of it being respect to xaxis it's respect to the yaxis. > Find the volume of the solid obtained by rotating the region bounded by y=x^2 , y = 0, and x = 3, about the yaxis. how do I solve this problem? @campbell_st
 7 months ago

pdd21 Group TitleBest ResponseYou've already chosen the best response.0
Do i solve it the same?
 7 months ago

campbell_st Group TitleBest ResponseYou've already chosen the best response.1
ok... so find the upper value of the curve at x = 3 so y = 9 this is similar to before dw:1386823955174:dw the values of a and b are a = 0 and b = 9 so you are looking at \[V = \pi \int\limits_{a}^{b} x^2 dy\] you have your equation in terms of x^2 so its \[V = \pi \int\limits_{0}^{9} y dy\] hope it makes sense
 7 months ago

pdd21 Group TitleBest ResponseYou've already chosen the best response.0
so, \[V=\pi \int\limits_{0}^{9} (x^2)\] I don't seem to be getting the correct answer ;/ @campbell_st
 7 months ago

pdd21 Group TitleBest ResponseYou've already chosen the best response.0
nvm! I caught my mistake! haha
 7 months ago

pdd21 Group TitleBest ResponseYou've already chosen the best response.0
Thankk you!(:
 7 months ago

campbell_st Group TitleBest ResponseYou've already chosen the best response.1
well because you are rotating about the y axis you integrate with respect to y \[V = \pi \int\limits_{0}^{9} y dy = 2\pi[\frac{y}{2}]^9_{0}\]
 7 months ago

campbell_st Group TitleBest ResponseYou've already chosen the best response.1
oops forgot the y^2... \[V = \pi \int\limits_{0}^{9} y dy = \pi [\frac{y^2}{2}]^9_{0}\]
 7 months ago
See more questions >>>
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.