- #1
olicoh
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Homework Statement
In Problems 11-15, let R be the region bounded by the lines y = −2x – 4, y = 6, and x = −2. Each problem will describe a solid generated by rotating R about an axis. Find the volume of that solid.
14) The solid is generated by rotating R about y = −3.
The Attempt at a Solution
R(x)=6-(-3)
r(x)=(-2x-4)-(-3)
A(x)=pi[(9)2-(-2x-1)2] = pi[81-(4x2+4x+1]
V=(pi) int[-5,-2](-4x2-4x+80)
=pi(-4/3x3-2x2+80x)[-5,-2]
Ok this is where I realize something is wrong because when I plug -5 and -2 into the equation, the number is negative, which is impossible since volume cannot be negative. I keep getting -774pi. Ah!