1. ## Calling On Mathletes

I promise, no one is doing my math homework for me, it's already been done, last week. I got a portion of a problem wrong in my math homework. I can't figure out how it's wrong and I sent a message to my instructor, last week. I haven't heard back from her, yet. I gave my fiance the equation and he came out with the same thing I did, so he can't help me. I was wondering if anyone else can do the equation and see what you come up with.

The question gives the equation 9x -6y = -6 and then asked if either of these two ordered pairs are solutions (4, -8), (10/3, 6).

For (4, -8) I put no, it is not a solution to 9x - 6y = -6 and I got that part correct.

For (10/3, 6) I put yes, it is a solution to 9x -6y = -6 and I got marked wrong by the program.

When I go through the "Help Me Solve" part, it explains every step of the first ordered pair. When I get to the second ordered pair, it stops at

9(10/3) - 6(6) = -6 and just tells you to simplify which is 9(10/3) = 90/3 which = 30 and -6 * 6 = -36.

30 - 36 = -6 so; -6 = -6. However, when I click "yes" it is a solution it tells me this:

"You answered yes. The correct answer is no because when the value of x and y are substituted into the equation, the right and left sides are equal."

I've gone through notes, the textbook and videos and I cannot find a single time when substituting ordered pairs is a true statement but not a solution.

If it's a glich in the system, I want my instructor to change my grade because that one problem is the reason I don't have 100% on my homework. Am I overlooking something or does it look like some sort of computer error?

2. You're right.

My guess is that someone took a calculator and did 10/3=3.3333333, 3.3333333*9=29.99999, 29.999999-36=6.00000001, 6,0000001 not equal to 6

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The second set is a unique solution, so the answer is yes.

Trust me, never worry about 100%. I've had term grades in math of 103% and 104%. I have yet to get an A++. As long as you get an A+, you can't ask for more.

4. Originally Posted by ShinAce
The second set is a unique solution, so the answer is yes.

Trust me, never worry about 100%. I've had term grades in math of 103% and 104%. I have yet to get an A++. As long as you get an A+, you can't ask for more.
I currently have a 93.3% average because I go into anxiety on quizzes and tests. I got an 88% on my only test because for 2 problems, I made stupid errors like 36/9 = 36 (yep, I did that) and on another question, I suddenly forgot how to divide fractions (I forgot to invert). The third mistake, I thought they were asking for a pair of numbers but they were only asking for a specific part of the pair. I need the 100% on lectures, homework, and discussion board to keep my overall average up.

Thank you both for your speedy replies.

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Originally Posted by closetgeek
I need the 100% on lectures, homework, and discussion board to keep my overall average up.
Wait, what? A grade on a discussion board? We only do lectures here, no homework. We don't even do organized lectures, just mostly rambling.

6. Originally Posted by closetgeek
The question gives the equation 9x -6y = -6 and then asked if either of these two ordered pairs are solutions (4, -8), (10/3, 6).
You are correct that (10/3, 6) is a solution to the given equation. Substituting, it boils down to -6=-6, like you got.

I do, however, have a couple of very minor nitpicks. In the equation 9x - 6y = -6, the minus sign on the left-hand side is the subtraction operator, not the sign of the 6y term. So when you carry out your substitutions:

Originally Posted by closetgeek
9(10/3) - 6(6) = -6 and just tells you to simplify which is 9(10/3) = 90/3 which = 30 and -6 * 6 = -36.
...you should get (30) - ((+)36). Of course, (30) + (-36) gives you the same answer, but, well, 6y = 6(6) = 36, not -36.

Also, it is not wrong to figure 9(10/3) = (9*10)/3 = 90/3 = 30. HOWEVER, it just seems easier to divide by the 3 first, so... 9(10/3) = (9/3)(10) = 3(10) = 30.

7. Originally Posted by HenrikOlsen
You're right.

My guess is that someone took a calculator and did 10/3=3.3333333, 3.3333333*9=29.99999, 29.999999-36=6.00000001, 6,0000001 not equal to 6
Except the response was that they were equal. Weird.
Originally Posted by closetgeek
"You answered yes. The correct answer is no because when the value of x and y are substituted into the equation, the right and left sides are equal."
Originally Posted by ShinAce
The second set is a unique solution, so the answer is yes.
Not unique. There is an infinite number of solutions. The equation represents a straight line, any of the points on the line are solutions.

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Originally Posted by grapes
Not unique. There is an infinite number of solutions. The equation represents a straight line, any of the points on the line are solutions.
Right, but the question asks if the ordered pair is a solution. As given, the second pair is a unique solution to the expression 9x -6y = -6. It most definitely is a unique solution would be my answer to the second part of the question.

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What Cougar pointed out about what the minus sign is
attached to is what caught my attention. Did you submit
your working of the problem? Even though you get the right

On the other hand, 90/3 was a lot more obvious to me than
9(10/3).

-- Jeff, in Minneapolis

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Originally Posted by closetgeek
"You answered yes. The correct answer is no because when the value of x and y are substituted into the equation, the right and left sides are equal."
Do you mind trying it again, because that sentence doesn't make sense. Does it say that the right and left sides are equal or are not equal. Either way, it's still just a typo on the teachers part.

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The meaning of that sentence is ambiguous.

-- Jeff, in Minneapolis

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If only I could figure out what ambiguous means.

Closetgeek: I like you dog! It's cute.

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The meaning of my statement was ambiguous, too, I see.

I meant that "The correct answer is no because when the
value of x and y are substituted into the equation, the right
and left sides are equal" could refer to what happens when
correct values of x and y are used, or it could refer to what
happens when the suggested values are used.

-- Jeff, in Minneapolis

14. Originally Posted by Jeff Root
What Cougar pointed out about what the minus sign is
attached to is what caught my attention. Did you submit
your working of the problem? Even though you get the right

On the other hand, 90/3 was a lot more obvious to me than
9(10/3).

-- Jeff, in Minneapolis
No I don't have to type anything out. The instructor on the videos always assigns the minus sign as a negative to the following number. It's just become habit for me to read it that way, now.

15. Originally Posted by ShinAce
Do you mind trying it again, because that sentence doesn't make sense. Does it say that the right and left sides are equal or are not equal. Either way, it's still just a typo on the teachers part.
It reads exactly as I wrote it. I thought maybe my blind spot was messing with me again, so I asked the Mr. to read it allowed as I typed it. It won't let me copy and paste from the page, though. It's not the teacher, this work is from an online text book, program.

16. Here is a screen shot of first, the homework page, and then the help me solve it page.

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Originally Posted by Jeff Root
The meaning of my statement was ambiguous, too, I see.
-- Jeff, in Minneapolis
I was just being sarcastic.

It appears there's been a glitch in the matrix causing your homework grade to be captured by agents. Any rescue attempt is going to be risky without the oracle's advice.

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It prompted me to specify the ambiguity I had in mind.
Without that, my assertion was lame.

-- Jeff, in Minneapolis

19. Originally Posted by closetgeek
I promise, no one is doing my math homework for me, it's already been done, last week. I got a portion of a problem wrong in my math homework. I can't figure out how it's wrong and I sent a message to my instructor, last week. I haven't heard back from her, yet. I gave my fiance the equation and he came out with the same thing I did, so he can't help me. I was wondering if anyone else can do the equation and see what you come up with.

The question gives the equation 9x -6y = -6 and then asked if either of these two ordered pairs are solutions (4, -8), (10/3, 6).

For (4, -8) I put no, it is not a solution to 9x - 6y = -6 and I got that part correct.

For (10/3, 6) I put yes, it is a solution to 9x -6y = -6 and I got marked wrong by the program.

When I go through the "Help Me Solve" part, it explains every step of the first ordered pair. When I get to the second ordered pair, it stops at

9(10/3) - 6(6) = -6 and just tells you to simplify which is 9(10/3) = 90/3 which = 30 and -6 * 6 = -36.

30 - 36 = -6 so; -6 = -6. However, when I click "yes" it is a solution it tells me this:

"You answered yes. The correct answer is no because when the value of x and y are substituted into the equation, the right and left sides are equal."

I've gone through notes, the textbook and videos and I cannot find a single time when substituting ordered pairs is a true statement but not a solution.

If it's a glich in the system, I want my instructor to change my grade because that one problem is the reason I don't have 100% on my homework. Am I overlooking something or does it look like some sort of computer error?
That looks exactly like mathxl.com.

EDIT - I am an idiot. I didn't see the screen shots. There are some little glitches in mathxl, but nothing too terrible. Then again, the glitches would stop you from getting a 100% on the homework.
Last edited by Solfe; 2012-May-31 at 03:08 AM.

20. Originally Posted by ShinAce
I was just being sarcastic.

It appears there's been a glitch in the matrix causing your homework grade to be captured by agents. Any rescue attempt is going to be risky without the oracle's advice.
I already sought out the oracle. She only speaks in binary so I am screwed!

21. Just to butt in: Your answer is correct. The second ordered pair is a valid solution. The error message is incorrectly applied and internally contradictory.

22. Is this this class College Mathematics (Mine was MT-125)? I had a similar issue with mathxl.com in this thread. My question involved pairs numbers for mid-points and it did some really weird stuff to me.

23. If I was you, I would tell the teacher to ask for their money back for that computer program...

24. Originally Posted by jokergirl
If I was you, I would tell the teacher to ask for their money back for that computer program...

It's fairly widely used, as I understand it. Luckily, I don't teach math.

cg, all I really know about MathXL is that it can do weird things sometimes. What did your teacher say when you asked about it?

25. Originally Posted by Tobin Dax
It's fairly widely used, as I understand it. Luckily, I don't teach math.

cg, all I really know about MathXL is that it can do weird things sometimes. What did your teacher say when you asked about it?
She said she spoke to someone at the program about the problem and being it was holiday weekend, that it should be fixed by Wed. As of last Wed, it hadn't been fixed. On Thursday, I emailed my teacher again but I haven't heard back yet. Friday I got on chat with support at MathXL and they told me that my teacher needs to go in and fix the grade. I told her that there is still the problem with the question and she told me to contact my teacher.

26. Originally Posted by closetgeek
She said she spoke to someone at the program about the problem and being it was holiday weekend, that it should be fixed by Wed. As of last Wed, it hadn't been fixed. On Thursday, I emailed my teacher again but I haven't heard back yet. Friday I got on chat with support at MathXL and they told me that my teacher needs to go in and fix the grade. I told her that there is still the problem with the question and she told me to contact my teacher.
Sorry you're not getting anywhere. I can understand that your teacher needs to fix your grade, and I'd probably just worry about that right now. Fixing the question will likely take some time to happen.

27. Our teachers and administrators need to have their acts together and have a plan B ready in case a buggy computer program evaluates a student's best efforts incorrectly.

28. Most teachers do, IME. Heck, if I'm ready for it . . . .

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Originally Posted by closetgeek
For (10/3, 6) I put yes, it is a solution to 9x -6y = -6 and I got marked wrong by the program.
You're correct. Program's wrong.

30. Here's the rub. Apparently there were two gliches in that assignment. I checked the score and it was the same, after my teacher said it had been corrected. Now, I got the last problem wrong. I looked at the answer and can't figure out how I arrived at that conclusion, but it's unlikely that someone got spiteful and went in to change my answer. The glich has been corrected by my score remains the same.

On another note; is it my nerd showing or are solving word problems, linear equations in 2 and 3 variables kind of fun?

On another note; our weekly assignment is broken up into teams of three. We are given a word problem and we have to create formulas to find the answers. The teams are supposed to work through the problem on the discussion board. I put up a post to start the thread on Monday and got no response. I sent private messages to my team and still got no response. WTH? Really? I am the type to get the discussion board questions done ASAP. There are about 5 of us that get the DB problems done on the day it's assigned. She couldn't stick me with that group? She had to put me in the group that pathologically leave everything for the last minute?

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