First, find the points of intersection of the two curves by setting them equal to each other:
3−x=x2+1 x2+x−2=0 (x+2)(x−1)=0 x=−2 or x=1 So the intersection points are at x=−2 and x=1. Now, we use the washer method to find the volume. The formula for the washer method is:
V=π∫ab(R(x)2−r(x)2)dx where R(x) is the outer radius and r(x) is the inner radius. In this case, R(x)=3−x and r(x)=x2+1. The limits of integration are a=−2 and b=1. So the volume is:
V=π∫−21((3−x)2−(x2+1)2)dx V=π∫−21(9−6x+x2−(x4+2x2+1))dx V=π∫−21(9−6x+x2−x4−2x2−1)dx V=π∫−21(−x4−x2−6x+8)dx V=π[−5x5−3x3−3x2+8x]−21 V=π[(−51−31−3+8)−(−5(−2)5−3(−2)3−3(−2)2+8(−2))] V=π[(−51−31+5)−(532+38−12−16)] V=π[(−51−31+5)−(532+38−28)] V=π[−51−31+5−532−38+28] V=π[−533−39+33] V=π[−533−3+33] V=π[−533+30] V=π[−533+5150] V=π[5117] V=5117π