#15 p411: consider the region bound by the curve y==x^2+1 and the line y==x+3
#15 p411: find the volume of revolution of the this region about the x-axis
show(solve(x^2+1==x+3,x))
show(integrate(pi*(x+3)^2,x)-integrate(pi*(x^2+1)^2,x))
show(integrate(pi*(x+3)^2,x,-1,2)-integrate(pi*(x^2+1)^2,x,-1,2))
show(integrate(pi*(x+3)^2,x,-1,2).n()-integrate(pi*(x^2+1)^2,x,-1,2).n())
plot([x^2+1,x+3],-1,2)