Problem: Increasing the radius of a cylinder by 6 units increases the volume by y cubic units. Increasing the altitude of the cylinder by 6 units also increases the volume by y cubic units. If the original altitude is 2, then the original radius is:
Answer Choices:
A. 2
B. 4
C. 6
D. 6Ο
E. 8
Solution:
V+y=Ο(r+6)2h=Οr2(h+6);β΄(r+6)2β
2=r2β
8
β΄3r2β12rβ36=0;β΄r=6.