Integration and volumesConsider the solid bounded by the two surfaces z=f(x,y)=1-x2 and z=g(x,y)=3x2 and the planes y=1 and y=-1 :The volume of this solid can be expressed as a double integral by subtracting a volume below g(x,y) from a volume below f(x,y) : Volume =D-dAWhere Alternatively, we could calculate a triple integral: volume =R-dVWhere R={(x,y,z)|(x,y)inD,z,}