Need help with Math problem (most likely simple for you people0

[cuber786]

I am working on a homework and came across a problem. I am horrible at this type of problem and I have to turn this assignment in online in 1 hour, so my question is, can anyone tell me the answer? (Btw this is not doing my homework for those of you that say I am not doing your homework since my homework is 12 questions long and this is only 1 problem)

Problem:

The profit from a product in thousands of dollars can be modeled by
P(n)=n^4 - 34n^2 + 225, where n is the number of thousands of units produced.
Factor to find the number of units produced in which the profit would be zero.

A) 2,000 units and 17,000 units
B) 3,000 units and 5,000 units
C) 5,000 units and 45,000 units
D) 9,000 units and 25,000 units

 

[Samlambert]

I am working on a homework and came across a problem. I am horrible at this type of problem and I have to turn this assignment in online in 1 hour, so my question is, can anyone tell me the answer? (Btw this is not doing my homework for those of you that say I am not doing your homework since my homework is 12 questions long and this is only 1 problem)

Problem:

The profit from a product in thousands of dollars can be modeled by
P(n)=n^4 - 34n^2 + 225, where n is the number of thousands of units produced.
Factor to find the number of units produced in which the profit would be zero.

A) 2,000 units and 17,000 units
B) 3,000 units and 5,000 units
C) 5,000 units and 45,000 units
D) 9,000 units and 25,000 units

If Im not mistaken you just have to write it as 0 = n^4 - 34n^2 + 225 and find the n using some zero's finding formulas, but I'm not sure, I didn't read everything and I didn't really try

EDIT: I just did that and ended up with 3 and 5, the answer is B

 

[pcharles93]

This does qualify as doing your homework though. It doesn't matter how much is done, it's still doing your homework. I don't think plagiarism is accepted by your teacher.

I get B also. Here's my thought process along with it.
0 = x^4 - 34x^2 +225
0 = (x^2 - 9)(x^2 - 25)
x^2 = 9
x^2 = 25
x = {3,5}

EDIT: 1 problem out of 12 is 8.33% so giving you one answer is giving you one letter grade. Quite an advantage over the other students, but if you can lie to yourself so you can ask us to give you the answer even though it is "doing your homework" even though it is just one problem out of 12.

 

[Odin]

This does qualify as doing your homework though. It doesn't matter how much is done, it's still doing your homework. I don't think plagiarism is accepted by your teacher.

I get B also. Here's my thought process along with it.
0 = x^4 - 34x^2 +225
0 = (x^2 - 9)(x^2 - 25)
x^2 = 9
x^2 = 25
x = {3,5}

EDIT: 1 problem out of 12 is 8.33% so giving you one answer is giving you one letter grade. Quite an advantage over the other students, but if you can lie to yourself so you can ask us to give you the answer even though it is "doing your homework" even though it is just one problem out of 12.

(S)he is asking us to do him/her a favor. We dont need to give him/her the answer.

P.S. What do you mean by "you people"?

 

[Todd]

I like the topic title 'Most likely simply....'

I have been looking at Pcharles93 post for 10 minutes now and cannot understand his thought process.

Im blown away I sucked in school.

 

[bamman1108]

I like the topic title 'Most likely simply....'

I have been looking at Pcharles93 post for 10 minutes now and cannot understand his thought process.

Im blown away I sucked in school.

He's factoring a trinomial. It looks much more difficult because it's not in the standard ax^2+bx+c=0 form.

This does qualify as doing your homework though. It doesn't matter how much is done, it's still doing your homework. I don't think plagiarism is accepted by your teacher.

I get B also. Here's my thought process along with it.
0 = x^4 - 34x^2 +225
(x^2+n)(x^2+n) - x^2*x^2 is x^4
0 = (x^2 - 9)(x^2 - 25) - a guess and check procedure finding two numbers that multiply to equal c and combine to create b
x^2 = 9
x^2 = 25
x = {3,5}

It's hard to explain easily. There's also the quadratic formula:

(-b+- the square root of [b^2-4ac])/2a

34+- the square root of 34^2-4(1)(225)

34+- the square root of 1156-900

34+- the square root of 256

(34+16)/2 = 25

(34-16)/2 = 9

x^2= 9, 25

x= 3, 5

 

[pcharles93]

I am working on a homework and came across a problem. I am horrible at this type of problem and I have to turn this assignment in online in 1 hour, so my question is, can anyone tell me the answer? (Btw this is not doing my homework for those of you that say I am not doing your homework since my homework is 12 questions long and this is only 1 problem)

Problem:

The profit from a product in thousands of dollars can be modeled by
P(n)=n^4 - 34n^2 + 225, where n is the number of thousands of units produced.
Factor to find the number of units produced in which the profit would be zero.

A) 2,000 units and 17,000 units
B) 3,000 units and 5,000 units
C) 5,000 units and 45,000 units
D) 9,000 units and 25,000 units

Or you can logic!! Since P(n) is profit and you're looking for the value at which you break even, you can set P(n) to 0. The 2 choices that look most promising to me are B and D seeing as how D is just B^2. One is probably just one mistake away from the other and since the first term is x^4 instead of x^2 that appears so often, I would stop and write down B right away.

 

[GerrySly]

I get B also. Here's my thought process along with it.
0 = x^4 - 34x^2 +225
0 = (x^2 - 9)(x^2 - 25)
x^2 = 9
x^2 = 25
x = {3,5}

Wow I have never seen factorising like that. I would factorise like this...
0 = x^4 - 34x^2 + 225
0 = ( x - 5 ) ( x - 3 ) ( x + 3 ) ( x + 5 )
x = +/-5, +-3
Then in my answer say that for all values x<0 are not valid and hence the answers are limited to +5, +3.

 

[MTGjumper]

You could substitute x in for n^2 and then get a quadratic. This factorises to 0 = (x - 9)(x - 25)

x = 9 so n = sqrt(9) = 3
x = 25 so n = sqrt(25) = 5

Just another way to look at this kind of polynomial, if you've never come across it before.