calc help!pleasee explain

Question

wade123 · Answer

@jim_thompson5910 last problem i dont get hahah if you could explain??

jim_thompson5910 · Answer

your image got cut off

wade123 · Answer

x=7 (:

jim_thompson5910 · Answer

are you able to graph the two equations? and see the region that forms between them?

wade123 · Answer

i will try that now(:

wade123 · Answer

attachment

jim_thompson5910 · Answer

you'll rotate that region in between the two graphs (in quadrant 1) around the vertical line x = 7

jim_thompson5910 · Answer

so you have to use your imagination a bit, but you'll have a donut shaped 3D solid

wade123 · Answer

and what do i do after??

jim_thompson5910 · Answer

check out example 2 on this page http://tutorial.math.lamar.edu/Classes/CalcI/VolumeWithRings.aspx it offers a visual explanation that may help. Let me know if it helps or not

wade123 · Answer

ohh thats exactly what were doing here

wade123 · Answer

the explanation isnt that great, i would prefer if someone did this problem with me

wade123 · Answer

@ganeshie8 could you explain??

jim_thompson5910 · Answer

imagine yourself looking down at the ring (from a bird's eye view)

you'd get something like this

|dw:1424573579250:dw|

jim_thompson5910 · Answer

|dw:1424573632826:dw|

are you able to generalize this region in terms of an integral?