College Math Problem

Off Topic
21

[quote]coolnatedawg wrote:

[quote]JLu wrote:

[quote]coolnatedawg wrote:

[quote]Tyrant wrote:

[quote]coolnatedawg wrote:
Man, just use the quadriatic equation.

Set the formula as 0=.1s^2 - 3s - 778 and throw that into the quadriatic equation.

I returned s= 104.5. Do I need to show my work?

(Note: It’s probably easier to do in a calculator but I wanted to use my brain before the zombies kill me and it serves me no purpose anymore)[/quote]

While that is the right answer its the wrong way to do it. By doing it like that you give yourself a parabola that opens up. Had the question also asked about the vertex of the parabola you’d be wrong. Remember that its y1-y2=0, not y1=y2 to get the formula[/quote]

I was just solving the part above the break in the question. My answer was either this or a negative number. I did not have to use y1 or y2. I simply used s=(b^2 +/- sqrt(b^2-4ac))/2a.

Right? Or do I not understand what you are saying? It’s been a while…
[/quote]
I think what he means is that while you’re technically finding the correct answer for s, you’re not doing it in the manner the question asks and thus wouldn’t get full marks since usually there’s more emphasis places on the process than the answer itself in these types of questions.[/quote]

Well then you think that would be an argument more in my favor then since a calculator wont show any work.

Also, the way I read the question, it tells you to solve the problem. It then says “to use the calculator to solve”. I interpret that as “if you are using the calc method, here is a hint.”

What teacher prefers you use a calculator over solving it by hand?[/quote]
Well I suspect the purpose of this exercise was to practice solving things using a graphing calculator, since this is a trivial question to solve. So with that in mind the intended solution was via the construction and interpretation of a 3rd graph (f(x) = y1 - y2) given 2 graphs, y1 and y2.

A teacher may prefer them to use a calculator since some types of math are simple by hand, just INCREDIBLY tedious, and thus when you are required to perform that step as part of a larger problem it allows you to avoid wasting time and energy on superfluous content (an example of simple but incredibly tedious work that is better handled by a calculator is finding the inverse of a matrix or the integral of a function such as cos^2(5x)*e^4x).

22

[quote]krayon wrote:

[quote]Tyrant wrote:

[quote]coolnatedawg wrote:
Man, just use the quadriatic equation.

Set the formula as 0=.1s^2 - 3s - 778 and throw that into the quadriatic equation.

I returned s= 104.5. Do I need to show my work?

(Note: It’s probably easier to do in a calculator but I wanted to use my brain before the zombies kill me and it serves me no purpose anymore)[/quote]

While that is the right answer its the wrong way to do it. By doing it like that you give yourself a parabola that opens up. Had the question also asked about the vertex of the parabola you’d be wrong. Remember that its y1-y2=0, not y1=y2 to get the formula[/quote]

I don’t understand what you are doing. I thought the question just asked to solve for s. I got (15,-0.5) for the vertex of the parabola. I used the “vertex form” y = a(x Ã?¢?? h)^2 + k.[/quote]

Actually, they are both kind of wrong; the question doesn’t ask about any parabolas, but it does give you the solution you are supposed to use on the problem, which coolnatedawg didn’t use. Of course the actual x-intercepts don’t change, but the equation is supposed to be -0.1s^2+3s+788=0

As to the OP’s question, I tried to figure out what he might have been doing wrong. I noticed that one solution for 0.1s^2-3s+22=0 is roughly s=17. I’m not sure how you could get results around 722. Forgetting the parenthesis for y2 should give around 76 (or 106 if you forget a minus sign in the denominator of the quadratic formula). Now it’s really bugging me how you got an answer around 722.

EDIT: Dammit, just how long was I typing that?

23

Given the fact that you couldn’t do this problem, paired with the fact that you posted for help on a bodybuilding forum, I set the over under for your test score at a C-.

24

[quote]Hertzyscowicz wrote:

[quote]krayon wrote:

[quote]Tyrant wrote:

[quote]coolnatedawg wrote:
Man, just use the quadriatic equation.

Set the formula as 0=.1s^2 - 3s - 778 and throw that into the quadriatic equation.

I returned s= 104.5. Do I need to show my work?

(Note: It’s probably easier to do in a calculator but I wanted to use my brain before the zombies kill me and it serves me no purpose anymore)[/quote]

While that is the right answer its the wrong way to do it. By doing it like that you give yourself a parabola that opens up. Had the question also asked about the vertex of the parabola you’d be wrong. Remember that its y1-y2=0, not y1=y2 to get the formula[/quote]

I don’t understand what you are doing. I thought the question just asked to solve for s. I got (15,-0.5) for the vertex of the parabola. I used the “vertex form” y = a(x Ã???Ã??Ã?¢?? h)^2 + k.[/quote]

Actually, they are both kind of wrong; the question doesn’t ask about any parabolas, but it does give you the solution you are supposed to use on the problem, which coolnatedawg didn’t use. Of course the actual x-intercepts don’t change, but the equation is supposed to be -0.1s^2+3s+788=0

As to the OP’s question, I tried to figure out what he might have been doing wrong. I noticed that one solution for 0.1s^2-3s+22=0 is roughly s=17. I’m not sure how you could get results around 722. Forgetting the parenthesis for y2 should give around 76 (or 106 if you forget a minus sign in the denominator of the quadratic formula). Now it’s really bugging me how you got an answer around 722.

EDIT: Dammit, just how long was I typing that?[/quote]

I was never very good at following directions on tests. I was always one of the kids that got caught when a teacher handed out a “trick” test saying to read the directions and do nothing else. I would always be working my way through a problem only to have the teacher smirking at my lack of attention.

That said, it was rather easy to interpret it the wrong way. Yeah, a clue in to how to do it graphically was presented, but it didn’t specifically say to do it that way. However, it does list to answer the solution as y1-y2=?. That’s the part where I am incorrect as I went about it my own way.

What grade do I get on this question? Do I even get partial credit?

PS- I got 10 internet dollars on the over. The curves in school are stupid

25

[quote]krayon wrote:
Is there another method to solve it without using the quadratic equation?[/quote]

You could ask people on a bodybuilding forum to do it for you.

26

[quote]coolnatedawg wrote:

[quote]Hertzyscowicz wrote:

[quote]krayon wrote:

[quote]Tyrant wrote:

[quote]coolnatedawg wrote:
Man, just use the quadriatic equation.

Set the formula as 0=.1s^2 - 3s - 778 and throw that into the quadriatic equation.

I returned s= 104.5. Do I need to show my work?

(Note: It’s probably easier to do in a calculator but I wanted to use my brain before the zombies kill me and it serves me no purpose anymore)[/quote]

While that is the right answer its the wrong way to do it. By doing it like that you give yourself a parabola that opens up. Had the question also asked about the vertex of the parabola you’d be wrong. Remember that its y1-y2=0, not y1=y2 to get the formula[/quote]

I don’t understand what you are doing. I thought the question just asked to solve for s. I got (15,-0.5) for the vertex of the parabola. I used the “vertex form” y = a(x Ã???Ã???Ã??Ã?¢?? h)^2 + k.[/quote]

Actually, they are both kind of wrong; the question doesn’t ask about any parabolas, but it does give you the solution you are supposed to use on the problem, which coolnatedawg didn’t use. Of course the actual x-intercepts don’t change, but the equation is supposed to be -0.1s^2+3s+788=0

As to the OP’s question, I tried to figure out what he might have been doing wrong. I noticed that one solution for 0.1s^2-3s+22=0 is roughly s=17. I’m not sure how you could get results around 722. Forgetting the parenthesis for y2 should give around 76 (or 106 if you forget a minus sign in the denominator of the quadratic formula). Now it’s really bugging me how you got an answer around 722.

EDIT: Dammit, just how long was I typing that?[/quote]

I was never very good at following directions on tests. I was always one of the kids that got caught when a teacher handed out a “trick” test saying to read the directions and do nothing else. I would always be working my way through a problem only to have the teacher smirking at my lack of attention.

That said, it was rather easy to interpret it the wrong way. Yeah, a clue in to how to do it graphically was presented, but it didn’t specifically say to do it that way. However, it does list to answer the solution as y1-y2=?. That’s the part where I am incorrect as I went about it my own way.

What grade do I get on this question? Do I even get partial credit?

PS- I got 10 internet dollars on the over. The curves in school are stupid[/quote]

I’ll give you half credit, while you did it wrong you still ended up with the right answer. I did this on a test recently and used operations of matrices instead of descartes rule…I don’t think I got any credit on it.

27

Oh, that could go terribly wrong depending on the teacher.

My pre-calc professor would deduct the value of the problem if you didn’t show work, but regardless of method, if you showed the work and it was wrong, she would deduct a point for each line past the mistake.

28

[quote]SkyzykS wrote:
Oh, that could go terribly wrong depending on the teacher.

My pre-calc professor would deduct the value of the problem if you didn’t show work, but regardless of method, if you showed the work and it was wrong, she would deduct a point for each line past the mistake.

[/quote]

Wow, mine was picky but man. If you messed up something on the first line, and then got the right answer of the messed up problem he’d only take 1-2pts off a 10 pt problem.

29

College? Seriously?

30

[quote]kakno wrote:
College? Seriously?[/quote]
These were my sentiments exactly. I know Americans go to college one year earlier, but this should still be a high school problem.

31

[quote]Hertzyscowicz wrote:

[quote]kakno wrote:
College? Seriously?[/quote]
These were my sentiments exactly. I know Americans go to college one year earlier, but this should still be a high school problem.[/quote]

Ok, that explains it. I’ve always been of the opinion that the Swedish school system is way too slow, especially compared to the Finnish, so when I opened this thread I expected an extremely intricate problem.

32

[quote]Tyrant wrote:
here’s a picture, its large. The inserted function is top left, and I switched the tic marks to increments of 104.5 to show the x-intercept. Good luck on your final[/quote]

How do you like them apples??^^^^

33

[quote]kakno wrote:
College? Seriously?[/quote]
Yeah this is definitely a question that would be considered simple even by high school standards.

34

[quote]JLu wrote:

[quote]kakno wrote:
College? Seriously?[/quote]
Yeah this is definitely a question that would be considered simple even by high school standards.[/quote]
Haha. It’s not suppose to be difficult. I did it correctly using my calculator but it came out wrong several times. When done on a different calculator it is correct. So i was like wtf.

35

[quote]Petermus wrote:

[quote]JLu wrote:

[quote]kakno wrote:
College? Seriously?[/quote]
Yeah this is definitely a question that would be considered simple even by high school standards.[/quote]
Haha. It’s not suppose to be difficult. I did it correctly using my calculator but it came out wrong several times. When done on a different calculator it is correct. So i was like wtf. [/quote]
Could just be the order you press the buttons and enter information since all calculators are different. This is why knowing your calculator well is critical to writing exams since you don’t have time to fumble around and second guess whether it’s producing the correct result or not.

36

[quote]Petermus wrote:

[quote]JLu wrote:

[quote]kakno wrote:
College? Seriously?[/quote]
Yeah this is definitely a question that would be considered simple even by high school standards.[/quote]
Haha. It’s not suppose to be difficult. I did it correctly using my calculator but it came out wrong several times. When done on a different calculator it is correct. So i was like wtf. [/quote]

You may also need new batteries in your calculator. I have a Ti and it gets funky when the batteries are low/dead.

37

If you have a TI, you could have the settings on radians instead of degrees. I remember that always made a difference when solving problems on graphs.

38

[quote]VTBalla34 wrote:
If you have a TI, you could have the settings on radians instead of degrees. I remember that always made a difference when solving problems on graphs.[/quote]
Except this time there aren’t any trigonometric functions involved, so I can’t think of a reason why it would matter.

39

[quote]kakno wrote:

[quote]Hertzyscowicz wrote:

[quote]kakno wrote:
College? Seriously?[/quote]
These were my sentiments exactly. I know Americans go to college one year earlier, but this should still be a high school problem.[/quote]

Ok, that explains it. I’ve always been of the opinion that the Swedish school system is way too slow, especially compared to the Finnish, so when I opened this thread I expected an extremely intricate problem.[/quote]

I know this is off topic, but I just want to add that my “college math” education started at this level; my remedial math courses (algebra/precalc) were taken at a two year community college and they did not count towards credit on my degree. Why did I have to learn such basic math while attending college? I dropped out of high school, and never learned any!

Of course, I did eventually take the standard calculus courses and all the CS theory/discrete math classes (earning an A in every single one, may I add). If it wasn’t for these remedial courses being offered, I may not now be a senior contemplating an offer to join a PhD program at my university.

40

[quote]Hertzyscowicz wrote:

[quote]VTBalla34 wrote:
If you have a TI, you could have the settings on radians instead of degrees. I remember that always made a difference when solving problems on graphs.[/quote]
Except this time there aren’t any trigonometric functions involved, so I can’t think of a reason why it would matter.[/quote]

Yeah I got to thinking about that later. You’re right. Its been a LOOOONNNNGGG time since I’ve had to use my TI calculator, much less had to solve for ‘x’ haha…carry on