Can Someone Help Me Make Sense of This Algebra Problem?

rcwitt · 2010-12-18 07:42:42

I am trying to figure this one out, but not having any luck. I have several problems that are similar to this one, so I really need to understand how to work it out.

I keep coming up with the answer 0x=-251. But I can't have a "0x" can I?

Thanks,
Charlie

Au101 · 2010-12-18 07:46:52

Hi Charlie, what have you tried so far?

Be careful, remember that there is a minus outside your brackets so you need to subtract everything within the brackets from that which is outside thereof.

rcwitt · 2010-12-18 07:58:09

I am new to this, so be gentle. LOL! I just returned to college after 20+ years and I am trying to "catch up". I believe I have a "natural" feel for math and can figure most things out.

Charlie

Last edited by rcwitt (2010-12-18 08:00:04)

Au101 · 2010-12-18 07:59:56

Of course I'll be gentle. Now why has the

in the original post become

?

Last edited by Au101 (2010-12-18 08:00:26)

rcwitt · 2010-12-18 08:01:09

It was a typo - the post showing my work is the correct problem. Sorry.

Charlie

rcwitt · 2010-12-18 08:04:34

Incidentally, the instructor I have for this class is one of those "I don't care if you learn it or not - I still get paid" (her actual words) type of teachers. So, she really hasn't been much help. I have learned more from this forum than the class I am paying for.

Charlie

Au101 · 2010-12-18 08:06:49

Oh dear, well good luck! I'm not sure that I think that much of this instructor. I get -251 = 0 as well and I can't see anything wrong with your algebra - although, if you don't mind me saying, you could probably have made your life a little easier in places. Perhaps your instructor's question was incorrect. Unless anybody can see our mistake?

rcwitt · 2010-12-18 08:09:36

The stated math problem came out of the textbook. Some of the problems that follow also come up with similar answers (ie. 0=-136). It really has me confused. Simply because 0=0, therefore, the statement 0=-251 cannot be correct.

Charlie

rcwitt · 2010-12-18 08:12:56

Also, I know that I tend to do some of the simplifying in an odd way, but it works out for me. I guess it's just the way I think. I have, in the past, deliberately tried to simplify them the way the online equation calculators do, but I find it easier to just do it the way that comes "naturally" for me. Provided I continue to get the correct answer, it works for me.

Charlie

Au101 · 2010-12-18 08:13:37

Well if we just look at the problem quickly we can see that there is -12x on both sides which must cancel. There is definitely an error here, are you sure that you have copied the question out correctly?

Au101 · 2010-12-18 08:18:28

Is it possible that the question is, in fact:

?

Last edited by Au101 (2010-12-18 08:19:07)

rcwitt · 2010-12-18 08:18:41

When I arrived at the strange answer, I double and triple checked. As I said, the following problem is similar:

rcwitt · 2010-12-18 08:20:12

The problems are written exactly as they are in the book. I don't know why I keep getting the strange answers. It really would have been nice if the instructor had explained the brackets to the class. It is my understanding that you perform the operations contained within the brackets first (similar to the parenthesis).

Charlie

Last edited by rcwitt (2010-12-18 08:22:27)

rcwitt · 2010-12-18 08:24:13

Au101 wrote:

Is it possible that the question is, in fact:
?

Incidentally, how would I go about solving the problem the way you have it written? I haven't learned that yet.

Charlie

Au101 · 2010-12-18 08:24:20

These questions are extremely odd, maybe we are both missing something, but I simply cannot see it, writing the equations in terms of x necessarily yields 0 = an integer.

rcwitt · 2010-12-18 08:25:31

That is exactly what I thought. 0x=-251 is an impossible statement.

Charlie

rcwitt · 2010-12-18 08:27:35

I did enter the equation into an equation calculator online to check my answer. The final answer it gave me was 1=1?!?!?! Which left me even more confused.

Charlie

***EDIT***
The calculator probably choked on the 0x=-251 answer. Sort of like an error on a calculator.

Last edited by rcwitt (2010-12-18 08:29:07)

Au101 · 2010-12-18 08:37:41

Hmmm...The famed Wolfram Alpha, which uses mathematica, returns no solutions to both questions. There is a definite error.

Last edited by Au101 (2010-12-18 08:38:02)

Au101 · 2010-12-18 08:39:17

With regard to your second question, this is much more difficult, have you ever done the quadratic formula before:

Last edited by Au101 (2010-12-18 08:39:28)

rcwitt · 2010-12-18 08:41:55

I have never heard of the quadratic equation. LOL. I quit school while in the 10th grade back in 1982 and haven't thought about algebra until now. I have been working in the construction field, so I have actually utilized some basic geometry (finding areas, volumes, etc) but I learned those in the field, in a hands on approach.

Charlie

Au101 · 2010-12-18 08:48:12

Okay, well you will need that formula to answer my more advanced question. If you like we could discuss that now, however, I'm still perplexed by these questions. I can say with some degree of certainty that there are no values of x which satisfy those equations. In mathematics, that is a perfectly reasonable result, indeed it can be a useful result. Indeed in formal texts it would not be uncommon to see something like:

Obviously you don't need to worry about that, it just says there aren't any values of x which satisfy that equation, I just thought you might be interested to see how we can conclude that the our equation has no answers. However, having finally got to the point of my post, it's not very useful in teaching algebra to give students equations which have no solutions. Does the book have any answers, or does the question say, at any point, something like which of these equations can you solve for x? For those which can be solved, find x?

Last edited by Au101 (2010-12-18 08:49:28)

rcwitt · 2010-12-18 08:56:38

The instructions for the problems are (quote)"In exercises 89-96, solve each equation."(end quote). Unfortunately, there are no answers in the book. I ought to write your answer just to mess with the instructor's mind. But, then she would think that I have a far better understanding of algebra than I actually possess. I guess I'll just leave it as is, with the 0x=-251 answer and see what she says. Thanks for all of your time and help.

Charlie

Au101 · 2010-12-18 08:58:45

Well it was a pleasure, please let me know if you get to the bottom of this :s

bobbym · 2010-12-18 10:30:42

Hi Charlie;

Those are certainly a little confusing. Take this one:

Which is obviously not true. There are no solutions. Not every equation anyone can write is valid. Some have no solutions. So just say no solutions. Glad you are learning latex.

Bob · 2010-12-18 15:29:54

Hi Charlie,

You originally said you had lots of problems like this. Unfortunately, the one you gave had an 'unhelpful' answer.

How about posting another?

Bob

Last edited by Bob (2010-12-18 15:31:43)

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#1 2010-12-18 07:42:42

Can Someone Help Me Make Sense of This Algebra Problem?

#2 2010-12-18 07:46:52

Re: Can Someone Help Me Make Sense of This Algebra Problem?

#3 2010-12-18 07:58:09

Re: Can Someone Help Me Make Sense of This Algebra Problem?

#4 2010-12-18 07:59:56

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#5 2010-12-18 08:01:09

Re: Can Someone Help Me Make Sense of This Algebra Problem?

#6 2010-12-18 08:04:34

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#7 2010-12-18 08:06:49

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#8 2010-12-18 08:09:36

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#9 2010-12-18 08:12:56

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#10 2010-12-18 08:13:37

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#11 2010-12-18 08:18:28

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#12 2010-12-18 08:18:41

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#13 2010-12-18 08:20:12

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#14 2010-12-18 08:24:13

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#15 2010-12-18 08:24:20

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#16 2010-12-18 08:25:31

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#17 2010-12-18 08:27:35

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#18 2010-12-18 08:37:41

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#19 2010-12-18 08:39:17

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#20 2010-12-18 08:41:55

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#21 2010-12-18 08:48:12

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#22 2010-12-18 08:56:38

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#23 2010-12-18 08:58:45

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#24 2010-12-18 10:30:42

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#25 2010-12-18 15:29:54

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