Question

11. A cylinder has a radius of 2x + 3 and a height of 6x + 1. which polynomial in standard form best describes the total volume of the cylinder? use the formula V= (Pie) r^2h for the volue of a cylinder.
A. 12(Pie) x^2+20(pie)x+3(pie)
B. 24(pie) x^3+76(pie)x^2+66(pie)x+9(pie)
C. 144(pie)x^4+480(pie)x^3+427(pie)x^2+120(pie)x+9(pie)
D. 72(pie)x^3+132(pie)x^2+38(pie)x+3(pie)
12. A sphere has a radius of 2x+5. which polynomial in standard form best describes the total surface area of the sphere? use the formula S=4(pie)r^2 for the surface area of a sphere.
A. 16(pie)x^2+80(pie)x +100(pie)
B. 16(pie)x^2+40(pie)x+100(pie)
C. 100(pie)x^2+80(pie)x+16(pie)
D. 100(pie)x^2+100(pie)

Answer 1

V=hpr^2  (for a cylinder)  we are given r=(2x+3) and h=(6x+1) so

V=p(6x+1)(2x+3)^2

V=p(6x+1)(4x^2+12x+9)

V=p(24x^3+72x^2+54x+4x^2+12x+9)

V=p(24x^3+76x^2+66x+9)  so B.

...

A=4pr^2 and r=(2x+5) so

A=4p(4x^2+20x+25)

A=p(16x^2+80x+100)  so A.

Answer 2

Its A. 16(pie)x^2+80(pie)x +100(pie) because,S=4(pie)r^2 for the surface area of a sphere.