Simplify the expression

Which of the following are parts of a sphere

Which of the following is most likely the next step in the series? a3z, b6y, c9x, d12w, е15v, f18u

Find the volume of the described solid.the solid lies between planes perpendicular to the x-axis at x = 0 and x=7. the cross sectionsperpendicular to the x-axis between these planes are squares whose bases run from the parabolay=-31x to the parabola y = 30/x.a) 441b) 147c) 864d) 882