Question

NEED HELP I DONT THINK IM DOING THIS RIGHT

Answer 1

1.Measure and record the diameter and height of the cylindrical object you have chosen in inches. Round to the nearest whole number.

2.Apply the formula of a right circular cylinder (V = r2h) to find the volume of the object. (Note: Be sure to find the radius from the diameter measurement by dividing by 2.)

Now suppose you knew the volume of this object and the relation of the height to the radius, but did not know the radius. Rewriting the equation with one variable would result in a polynomial equation that you could solve to find the radius.

3.Rewrite the formula using the variable x for the radius. Substitute the value of the volume found in step 2 for V and express the height of the object in terms of x plus or minus a constant. For example, if the height measurement is 4 inches longer than the radius, then the expression for the height will be (x + 4).

Answer 2

1. D= 4in.
H= 6in.
2. 3.14 (2^2)6 / 3.14(4)(6)= 75.36
3. 75.36= 3.14x^2(6)
4.

Answer 3

and number 4 says,,,
Simplify the equation and write it in standard form. Multiply each term in the equation by 100 to eliminate any decimals, if necessary.

Answer 4

ugh... ugly boring word problem....

Answer 5

thank you captin obvious -_-

Answer 6

Hey, believe it or not some math problems are interesting
this is not one of them...
well go find a cylindrical object
got a soda can handy ?

Answer 7

i posted what i did look up a few comments i did 1-3

Answer 8

but im not sure if im even doing it right

Answer 9

for part 3 it says
"express the height of the object in terms of x plus or minus a constant."
you missed that part

Answer 10

up 'till then it's fine

Answer 11

ok well how do i do that

Answer 12

if the radius is 2, and the height is 6
then if we call the radius x the height is x+?
what is "?"

Answer 13

6?

Answer 14

let's try it:
radius=x=2
h=6=x+6=2+6
but we wanted h=6, so...

Answer 15

if the radius is x=2 and the height is h=6
then h=x+4
(because 2+4=6, make sense ?)

Answer 16

yes 2+4=6 make sance

Answer 17

so we can write the height in terms of the radius x
h=x+4
sub that in for the height in your formula

Answer 18

so h=x+4 is the answer for #3? this is confusing

Answer 19

no, you just have to put x+4 where the value of the height was in formula #3
what is the height ?

Answer 20

so if i wrote 75.36= 3.14x^2(6) and 6 is the h then its 75.36= 3.14x^2(x+4)?

Answer 21

exactly :)

Answer 22

ok so my questain befor if i have 75.36= 3.14x^2(x+4) then how do i..

4. Simplify the equation and write it in standard form. Multiply each term in the equation by 100 to eliminate any decimals, if necessary.

5. Find the solutions to this equation algebraically using the Fundamental Theorem of Algebra, the Rational Root Theorem, Descartes' Rule of Signs, and the Factor Theorem.

Answer 23

oh you got a whole grip of stuff here...
for part 4 get rid of the decimals first
(like they say, multitply everything by 100)
what do you get?

Answer 24

do i keep the equation and just multiply each number individually?

Answer 25

yes, only the coefficients are effected

Answer 26

*affected

Answer 27

whats a coefficient thing?

Answer 28

the number next to the variable(s):
in
3x -> 3 is the coefficient
in
5.14y -> 5.14 is the coefficient
in
24.58793xyz -> 24.58793 is the coefficient

Answer 29

ok so 75.36= 3.14x^2(x+4) my answer is 7536=314x^2(x+4)?

Answer 30

yes, but now you can distribute the \(314x^2\) on the right side to the \(x+4\)

Answer 31

so 314x^2(x+4)... i dont know how to do that :(

Answer 32

law of distribution\[a(b+c)=ab+ac\]

Answer 33

so 314x^3+ 1256?

Answer 34

prolly, let me check my calculator for 314(4)

Answer 35

yeah that's right
now as far as what they mean by "standard form" I think they mean all = to some constant

Answer 36

so thats my answer for 4?

Answer 37

oh wait, you forgot to distribute the x^2 on the 4...
so the whole expression is\[7536=314x^3+1256x^2\]

Answer 38

so set all that equal to zero:
that is standard form

Answer 39

ok so now thats the answer to 4?

Answer 40

I think they want it set to zero, but I'm not sure; different people use "standard form" differently believe it or not.

Answer 41

well im not looking to get %100 on this assingment if that part is wrong then its fine

Answer 42

also you should see if you can simplify it (you can)
notice all the coefficients are even, so we can at least divide by zero

Answer 43

once it is in standard form and simplified you use the rational root theorem to solve the cubic, which may be a pain depending on what the simplification turns out to be.

Answer 44

7536=314x^3+1256x^2
7536=1570x^5?

Answer 45

no, you can't add exponents unless you are multiplying...
it stays as
7536=314x^3+1256x^2
but divide both sides by 2 for a start...

Answer 46

3768=157x^3+628x^2

now I'm not so sure it can be simplified any more...

Answer 47

7536=157x^3+ 628x^2?

Answer 48

\(both~~sides\)

Answer 49

anyway, all I see offhand is to set it all =0

Answer 50

so subtract off the RHS

Answer 51

whats RHS ?

Answer 52

my mistake:
subtract off the LHS

RHS=right-hand side
LHS=left-hand side

Answer 53

3768=157x^3+628x^2 ...subtract the left of what?

Answer 54

3768
is the LHS
subtract it from both sides and your equation will then be
(blah blah blah)=zero

Answer 55

i still dont get it

Answer 56

subtract 3768 from both sides....
3768-3768=157x^3+628x^2-3768

Answer 57

0=157x^3-3140?

Answer 58

3140x^2

Answer 59

hopefully you mean
0=157x^3+628x^2-3768

..where did you get 3140 ?


oh I see... no those are not like terms, so you can't combine them

Answer 60

yha idk what i did i just know im confused

Answer 61

o wait i think i get it so its that the answer to 4?

Answer 62

looks like it

Answer 63

as far as part 5....
you've obviously missed way too much to try to explain how you might try to solve this using the techniques they mention, so I'll have to opt out on that one.

Answer 64

um ok thanks for getting me this far

Answer 65

you're welcome
honestly I would only solve the last problem with a computer, the difficulty being that you can choose any numbers for the dimensions of the cylinder, so the problem is likely to turn out ugly (as it has).

good luck to those who would solve it from here without a computer!