Question

please i really need help been stuck on this for an hour will fan and medal if you are right
A cylinder has a radius of 5x+2 and a height of 2x+8. Which polynomial in standard form best describes the total volume of the cylinder?
Use the formula V = Pi r^2 h for the volume of the cylinder.
A.) 100pi x^4 + 880pi x^3 + 2256pi x^2 + 1408pi x + 256pi
B.) 50pi x^3 + 240 pi x^2 + 168pi x + 32pi
C.) 20pi x^3 + 168pi x^2 + 384pi x + 128pi
D.) 10pi x^2 + 44pi x + 16pi

Please help, it'd be greatly appreciated!

Answer 1

Ok do it with me, r(x)=?

Answer 2

where r is the radius

Answer 3

i just dont know if i have the right answer would you be able to tell me if i have the answer or not?

Answer 4

yea, but I haven't done it yet so tell me then i'll let you know

Answer 5

i got C

Answer 6

I did not g;et c

Answer 7

B?

Answer 8

no guessing, let's try and do it. First let's eliminate one answer right off the bat

Answer 9

ok by by C :)

Answer 10

So what is the highest exponent you can actually get with this problem?

Answer 11

well actually i was planning on that but we can get rid of C too

Answer 12

what were you going to say?

Answer 13

How many times does x show up?

Answer 14

3

Answer 15

?

Answer 16

yup so the highest exponent we can have is?

Answer 17

3 correct?

Answer 18

yea, so which answer can we also eliminate

Answer 19

A!

Answer 20

its b right?

Answer 21

Good we can eliminate A. I'm not telling you the answer yet so now

Answer 22

let's sub our r(t) and h(t) values in

Answer 23

oops that should be r(x) h(y)

Answer 24

i know its b! because theres only 2 exponents when there should be 3!

Answer 25

oh yea, well that is true, but i wanted you to do the multiplication haha

Answer 26

it's an important method to learn

Answer 27

yeah i know i was just tired of this question

Answer 28

lol well at least read this for me and remember that the squared actually means (5x+2)(5x+2) http://www.purplemath.com/modules/polymult2.htm

Answer 29

will do thank you!

Answer 30

np, medal please?