Asked by Jane
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? The choices are:
2pi(3x^2 + 10x - 8)
2pi(12x^2 + 7x - 2)
2pi(12x^2 - 2x + 13)
2pi(12x^2 - 5x - 2)
Please help me in setting this up and solving. Thanks
2pi(3x^2 + 10x - 8)
2pi(12x^2 + 7x - 2)
2pi(12x^2 - 2x + 13)
2pi(12x^2 - 5x - 2)
Please help me in setting this up and solving. Thanks
Answers
Answered by
Knights
surface area = 2pi (r^2 + rh)(it is the formula)
So, we just plug it in.
ignoring the 2 pi, we see that r^2 = (3x-2)^2 = 9x^2-12x+4
r*h = (3x-2)(x+3)
Then we get for rh = 3x^2-2x+9x-6 =
3x^2 +7x-6.
We add these together to get 12x^2 -5x-2
multiply by 2pi we get
2pi(12x^2-5x-2)
That is the answer and thus it is D
So, we just plug it in.
ignoring the 2 pi, we see that r^2 = (3x-2)^2 = 9x^2-12x+4
r*h = (3x-2)(x+3)
Then we get for rh = 3x^2-2x+9x-6 =
3x^2 +7x-6.
We add these together to get 12x^2 -5x-2
multiply by 2pi we get
2pi(12x^2-5x-2)
That is the answer and thus it is D
Answered by
Pewe
1.A
2.D
3.B
4.D
5.C
2.D
3.B
4.D
5.C
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