4. The radius of a cylinder is 3x – 2 cm. The height of the cylinder is x + 3 cm. What is the surface area of the cylinder? Use the formula A = 2r 2 + 2rh.

Question

4.   The radius of a cylinder is 3x – 2 cm. The height of the cylinder is x + 3 cm. What is the surface area of the cylinder? Use the formula A = 2r 2 + 2rh.

anonymous · Answer

attachment

lgbasallote · Answer

do you mean 2 pi r^2 +  2 pi rh?

try substituting...r= 3x-2
h = x+3

so...

2 pi (3x-2)^2 + 2 pi (3x-2)(x+3)

ill factor out 2 pi (3x-2)...

2pi 3x-2(3x-2 + x-3)
2pi (3x-2)(4x-5)
2pi(12x^2-23x + 10)

4 pi x^2 - 46 pi x + 20pi

is that in the choices?

anonymous · Answer

no it not

lgbasallote · Answer

not any of the values in the steps?

anonymous · Answer

2(3x^2 + 10x – 8)

lgbasallote · Answer

i dunno how they got that sorry :(

directrix · Answer

Total Area = Lateral Area and Base Areas
TA = (perimeter of base)*h + 2 (pi r^2)
TA = 2 pi( r) (h) + 2 pi (r) ^2
TA = 2 pi ((3x - 2) (x + 3) + 2 pi (3x - 2)^2
TA = [ (2 pi) (3x - 2) ] [ ( x + 3 ) + (3 x - 2) ]
TA = [ (2 pi) (3x - 2) ] [ 4x + 1]
TA = 2 pi [ 12 x ^ 2 - 5 x -2 ]  ----> Last Option