Math Question

Gigazombie Cybermage

I'm having problems in Math 1010, and before you laugh, know that I've never even went to high school (Got yanked out my first freshmen semester) and I'm making a 3.5 GPA. (For now anyways, I also seem to be having problems in Spanish that they're making me take)

Anyways, here is the problem.



I come up with x = 7 and 1/7, but my answer sheet says 12.5, and I can't figure out what I did wrong. Here is how I got the answer.

2x + 5x + 3x=3x + 50
-3x -3x
2x + 5x = 50
7x = 50 then 7x/7 = 50/7

50/7 = 7 and 1/7

This is all very frustrating, since if I fail there won't be any coming back, I'm paying my way through college with pell grants and loans, and hopefully scholarships. It's imperative that I maintain my GPA with a respectable number.

Essee

Just curious, where is the "+ 3x" on the left coming from? I haven't done geometry in a little while, but I don't see where you got it based on the image. And if that's not there,
2x + 5x = 3x + 50
-3x -3x
4x = 50
x = 12.5

Gigazombie Cybermage

Edit: Oh, I see what I did. Thanks! I'm an idiot, apparently.

Skoal Cat

No image is loading.
Is

2x + 5x + 3x=3x + 50

what is in the book, or is that after your first step?

Essee

Hmm. The textbook says it's there, even though it wants you to use that image as a basis? Well that's strange unless there's something I'm really missing here. Uhhh, I guess I'll have to think on this a bit more in that case... What exactly does the textbook say?

Edit: I've never been able to get 80% of the images to load automatically on the new forums, but if you right-click > View Image it does show up.

Gigazombie Cybermage

I'll leave this thread open, because I'm an imbecile when it comes to math. I have another one. I have to find a numerical measures of angles of the triangles. Normally so simple a baby could do it. But again I'm getting an answer different than the answer sheet. The answers the teachers gave us is 25, 65, 90, but here's what I did.

X+3x-10+x+10=180
5x=180 so /5
x=36

36+108-10+36+10=180
36+98+46=108
So I end up with 26, 98, 46 instead of what's on my answer sheet.

Gigazombie Cybermage

Er, did I ask a stupid question? <<;

GoodOmens

You're making the second part of the problem WAY too complicated. You've got the value x=12.5. Just plug it into 2x and 5x and you'll have the values of those two angles. Subtract those from 180, and you'll have the third.

Gigazombie Cybermage

Oh sorry, I should have clarified. It's a different problem now. The second problem doesn't give me an illustrated triangle.

Skoal Cat

I feel like we're not being shown something though, because I have no idea the context for your second problem.

Essee

I get the feeling that this is another case of us not being able to see the original question being asked? Especially because there's -10 + 10 in the problem, that seems a little weird for being the initial starting point. By the way, don't feel bad for making "dumb" mistakes! I think this really happens to just about everyone who does math, periodically. Then again, maybe NOT everybody since it did turn out I switched majors when I got to Calculus II... :P

Gigazombie Cybermage

The book says and I quote: "Find the numerical measures of the angles of the triangle whose angle measures are given in problems 35-40."

I've done number 36, because it was easy-peasy. (x, x, 2x)

But question 40 had me confused because the answer that the teacher gave me is different than the one I got. (see above)

Edit: This is exactly how it is in the book... for realz this time. ;P
x, x - 10, x + 10

I think he has the wrong answer down for the problem, I noticed the answer he gave is the answer for numer 38. (We're supposed to do 4-48, every 4th problem)

Gigazombie Cybermage

Well, I'll email him about it anyways.

Malyonsus

I'm not sure I understand the problem.

Is it that you have a triangle whose angles are defined as (x, x - 10, x + 10)? If that's the case you have

x + x + 10 + x - 10 = 180

I'm not sure where 'x + 3x - 10 + x + 10' came from. Specifically the 3x. Maybe a copy error?

At any rate, if the teacher has 25, 65, 90 as the answer, it's almost certainly associated with the wrong question.


Edit: Similar triangles are triangles that have the same three angles (but different length sides). All triangles with, for example, angles 45, 45, 90 are similar. If you know just the sides, two triangles would be similar if there exists a number 'n' such that each side in one triangle times n equals a side in the other triangle. For example a triangle with sides '3,4,5' and a triangle with sides '6,8,10' are similar because the second triangle has sides twice as long as the first.

Gigazombie Cybermage

Yeah, you have the right of it Malyonsus. I can actually do the problem easily, but my answer was really different than his is what was causing the confusion.

Tox

Do yourself a favor. Before checking the answer sheet, take the results you got, and plug them back into the equation. That should reveal whether or not you got it right. This is a helpful habit because when you're actually taking a math test, you don't get the answer sheet to compare to.

Demerdar

I also think you need to take some time and set the problem up correctly. I'm having a really hard time even following what you are asking. Half the battle is taking the question and setting it up correctly.

Gigazombie Cybermage

Er, sorry. I've never been very good at expressing myself.