12 Find a simplified polynomial expression in terms of x for

12. Find a simplified polynomial expression in terms of x for the surface area of the figure. X 4 13. Find a simplified polynomial expression in terms of x for the volume of the box below. 3x +1 2x 1

Solution

12) Closed cylinder

Total surface area = 2*pir^2 + 2pi*r*i   where r = radius and l = length

So, r = x ; length, l = x+4

Surface area = 2pi*x^2 + 2pi*x(x +4)

= 2pix^2 + 2pix^2 + 8pix