I have seen the future.

Expand:
(x-a)(x-b)(x-c)(x-d)( ... )(x-y)(x-z)

No. :P

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Oh, come on, you can't just do it in your head?

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unnamed525.livejournal.com

Yes, but I don't want to give it away.

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I stopped having to do trick questions after I graduated high school and was no longer on the math team.

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I COULD do this one quite easily in about four hours of painstaking work, but I'm betting there's a quick trick involved and I don't know what it is.

And considering that I definitely passed high-school algebra, you're full of it!

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Since you passed high-school algrebra, you SHOULD be able to do this one in your sleep. If you're awake, then doing it in your head will suffice.

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Oh. Duh. Yeah, I just looked it up.

Ok, see, this is not a quick trick, it's a lame-assed doesn't-count trick kind of question, where if you were a real mathematician, you'd x' it.

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elffin.livejournal.com

Google is your friend.

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dreamshade.livejournal.com

Har har, I should be able to do trick questions in my sleep. :p

The croc has a point - if you were stupid enough to think junior high algebra teaching would be a rewarding career...

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bluetara2020.livejournal.com

x-x = 0

-coughs-

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You know, I actually failed high school algebra (passing because he decided to grade on a curve is not passing), and my reason then is the same as my reason now.

Don't care, will never use this.

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a-pawson.livejournal.com

The answer is 0.

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katballou.livejournal.com

I'm just amused that if you google it the second result is this entry.

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marlo.livejournal.com

OOH! OOH! The answer to the comic is x=3!

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glitteringlynx.livejournal.com

For the record, I never took the actual OAC Algebra course. I only learned some of it in the first four high school grades as one section of the course. Also, I'm not great at math. The best math grade I ever got was for OAC Finite (that was a fun course!).

So.. I have no idea what the trick is to your math problem you gave.

However I *can* do this one:

3x+4=13
3x=13-4
3x=9
x=3

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For the original quesiton: What's the third term from the end?

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glitteringlynx.livejournal.com

(x-x)

Oh, wait...

*smacks forehead*

I get it now. :)

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torrain.livejournal.com

Yeah, that was pretty much my thought process, complete with mad delay.

I did pretty well in algebra, as I recall, although calculus kicks me to the curb and back every time I even approach it. But it's been years since I've used it, and so I was rusty enough to miss that.

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glitteringlynx.livejournal.com

I graduated from high school in June 1999 (we had a fifth year in high school called OAC). I took calculus becuase I had to.. and did TERRIBLE. I was just happy I passed.

The algebra units we did in the 4 grades prior I did rather well at, once I got the hang of things. But I didn't take the actual course in algebra because.. well.. I hate math. I was far more of an English/Music person in high school.

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anivair.livejournal.com

yeah, I felt stupid, too.

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So.. I have no idea what the trick is to your math problem you gave.

Any operation contained in parentheses is performed first. In the case of all the other terms, those operations cannot be done, because the values of the variables are not known. However, assuming the sequence of the expression is truly alphabetical, the third-to-last term is (x-x). By the reflexive property, x = x, and thus x - x = 0. By the zero property of multiplication (no really, that's what it's called), anything times zero is zero. Therefore, the entire expression is equal to zero, and

theweaselking is kind of a jerk.

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Well, the way I was looking at it, when he says "Expand", it does mean it can be done, but yeah, you end up with a bunch of constant letterings that just get longer and longer the more you "expand".

(x-a)(x-b) = x² - ax - bx + ab .. lather rinse repeat. It would get rather long without the "trick" by the end, though!

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The key is order of operations. Because (x-x) is in parentheses, if you don't do that operation first, you're technically not doing it right.

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Well, they're ALL in parentheses, right? So if you go left to right, which is like TOTALLY legitimate and stuff, expanding the parentheses as you come to them, you're fine. (x-a)(x-b) is just one step in the looong road that you'd take until you got to (x-x) and said "well, fuck."

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expanding the parentheses as you come to them

Nope, each set of parentheses takes precedence. So you go through left to right, leaving each set as you find it because it is already as simplified as possible, until you get to (x-x), which can be further simplified.

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I learned Order of Operations differently from you! But you would win, because your work makes things easier.

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toddhamster.livejournal.com

But if you expand the expression algebraically, say, from left to right,
you end up with an expression equivalent to the original, only written differently. This does not violate the order of operations, it is just
an expansion.

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And, because of the x-x term, eventually *all* of your expanded results will cancel out.

x^26 - x^26 + 25(x^25)a - 25(x^25)a + etc.

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scifantasy.livejournal.com

(Responses unseen yet...)

0.

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http://users.livejournal.com/_jeremiad/

I swear, sometimes I'm convinced I have dyscalculia.

Numbers are just not intuitive to me.

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the-colombian.livejournal.com

I go with the following equation:

Whatever math I need to count, multiply, or subtract from the money in my bank is all I'll ever need.

All other free time will be spent having sex with an attractive woman.

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http://users.livejournal.com/_jeremiad/

*snicker*

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atesh42.livejournal.com

Killface: And what do you think you're doing?
Simon: [mutters]
Killface: Oh, really? Well, bright young lads who bring home a C in earth science and a C minus in algebra don't get to go on a lovely kidnapping.
Simon: [mutters]
Killface: Yes, as a matter of fact, we'll probably use algebra like mad today.

(deleted comment)

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Oh god! This shows up on the WoW forums all the time.

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Without even looking at it, I said "it divides by zero".

And I was right.

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jerril

Just to be complete here (SPOILER ALERT SPOILER ALERT):

(SPOILER ALERT SPOILER ALERT)

(SPOILER ALERT SPOILER ALERT)

(SPOILER ALERT SPOILER ALERT)

a=b
Therefore the term (a-b) is just another way of writing 0.

So between line 4, and line 5, when they eliminate the (a-b) terms on both side by dividing both sides by (a-b), they're actually dividing by zero.

-----

For those of you who may not be getting how that makes (a-b) go away (I know at least one of John's readers didn't, because I got asked about this):

pretend the left side is X*Y, not (a+b)(a-b)

you can eliminate Y by dividing by Y ...

X*Y/Y = X...

because Y/Y = 1, and anything * 1 is itself.

The whole term can be eliminated this way... except that the whole term is equal to zero, so you can't, so you get a nonsense answer.

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I had to go through it five times *despite this explanation* before I finally figured it out.

I hate math, it makes me feel stupid.

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Whenever you see a nonsensical result, look for where they've divided by zero.

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That doesn't help me actually understand the problem itself, or make it any easier to find the spot where they've done so. :P

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It should. You're *not* dumb, and you've seen through harder problems.

Okay, pop quiz: someone at your workplace has a physical document, printed double-sided. They want a single PDF with all the pages, in order. However, the scanners will only scan one side of a multi-page document at a time, and nobody has a copy of Acrobat Professional or Foxit Editor to combine the scanned PDF of side 1 with the scanned PDF of side 2.

What now?

PS: Trial versions of both pieces of software ARE available, but both of them watermark the output unless you pay, and
A) nobody is willing to pay
B) a watermark is not acceptable.

Therefore, a trial version of either software is NOT a workable option.

Pop quiz. Your solution?

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1) Our scanners handle both sides of a multi-page document.
2) We have Acrobat Pro.
3) Lacking either, we'd BUY ONE OF THE TWO to avoid using the solution below.

That said, lacking both I'd scan each side separately, load the images into Word (or whatever, really - I like Word because it will give me nice neat pages and auto-resize the image to fit them), use PDFcreator to 'print' to a PDF, problem solved.

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Your solution involves software not in the original solution. But works, given that I did say "your workplace".

My solution was

1) Scan each side separately into a separate PDF. So I have side1.pdf and side2.pdf
2) Print one of them, single sided. Assume it's side2.pdf.
3) Interleave the original print job with the one I printed in step 2, such that I now have a full SINGLE-SIDED printout of the document.
4) Scan the full 2xpage document as a "single document", into a single PDF.

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ungratefulninja.livejournal.com

Yes, sometimes people really do need a problem solved and don't have money to spend solving it. However, in the workplace, the answer "In order to do X acceptably, I need Y" is a valid answer.

Earlier post fueled by ethanol and work rage.

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When a 1200dpi scan is just 3 minutes more than a 100dpi scan, sometimes it's not worth arguing with The Money for the $60 it takes to make scanned PDF editing a possibility.

And the alternative - scan to JPG, open in Word with 1 JPG = 1 page, print to PDF using PDF Creator - is more annoying, if slightly faster.

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jerril

The problem with this as a solution is it results in scanning a printed scan of the document, which results in quality loss, which makes my teeth curl.

Of course, apparently most office people have no problem with printing something, faxing it, scanning the fax, printing it, writing on it, and faxing it again. But they're barbarians.

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