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Topic: Simplifying Algebraic Expressions with Subtracted Expressions
Replies: 67   Last Post: Nov 25, 2013 12:57 PM

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 Robert Hansen Posts: 11,345 From: Florida Registered: 6/22/09
Re: Simplifying Algebraic Expressions with Subtracted Expressions
Posted: Nov 14, 2013 3:55 PM
 att1.html (6.8 K)

On Nov 14, 2013, at 2:19 PM, Joe Niederberger <niederberger@comcast.net> wrote:

> Yes, I see that, but is that not, (more explicitly):
> [1] (3/5)x - (1/4(1-3/5)x) = 200 ?
>
> Not exactly the same starting point, and the x really is there, done that way. Has to be.
>
> More explictly, the Ma version would be:
> [2] x = 200 % (3/5 - 1/4(1-3/5))
>
> But since the x is already isolated, I will grant the point that this is "arithmetic". But, although one can sweep that little first step that leads from [1 expression to Ma's under the rug of "done in the head", I think that would be a cheat.

I am saying that Ma's problem really isn't any different than the following problem that we do "in our head" ...

"Tom has 4 boxes and 200 donuts, how many donuts go in each box?"

This decodes to...

(4) Donuts Per Box = 200

In Ma's case, the problem decodes to...

(3/5 - 1/4(1-3/5)) Total Tarts Made = 200

The trick is reading the Ma problem directly into the coefficient (3/5 - 1/4(1-3/5)) in one pass, which seems foreign to us, but isn't really that hard, especially if you don't know algebra. So, in a sense, it is a harder reading problem but a simple arithmetic problem.

Yes, there is an implicit unknown in all problems, but, unless it requires algebra, then I don't call it "cheating" when you do these sorts of problems in "one step". How about 1.5 steps? To me, 2 steps implies that you have to look at the result of step 1 and make another decision, which is not the case here.

Bob Hansen

Date Subject Author
11/11/13 MVTutor
11/11/13 Robert Hansen
11/12/13 Bishop, Wayne
11/12/13 MVTutor
11/13/13 Jonathan J. Crabtree
11/13/13 Bishop, Wayne
11/14/13 Joe Niederberger
11/14/13 Robert Hansen
11/14/13 Joe Niederberger
11/14/13 Robert Hansen
11/14/13 Joe Niederberger
11/14/13 Robert Hansen
11/14/13 Louis Talman
11/14/13 Joe Niederberger
11/14/13 Robert Hansen
11/14/13 Robert Hansen
11/16/13 Bishop, Wayne
11/16/13 Robert Hansen
11/14/13 Joe Niederberger
11/14/13 Robert Hansen
11/16/13 Bishop, Wayne
11/14/13 Pam
11/15/13 Robert Hansen
11/15/13 Joe Niederberger
11/15/13 Robert Hansen
11/15/13 Joe Niederberger
11/15/13 Joe Niederberger
11/15/13 Joe Niederberger
11/15/13 Robert Hansen
11/16/13 Bishop, Wayne
11/16/13 Robert Hansen
11/17/13 Bishop, Wayne
11/17/13 Robert Hansen
11/17/13 Bishop, Wayne
11/15/13 Joe Niederberger
11/15/13 Robert Hansen
11/15/13 Pam
11/15/13 Robert Hansen
11/15/13 Pam
11/16/13 Robert Hansen
11/16/13 Robert Hansen
11/16/13 Joe Niederberger
11/16/13 Robert Hansen
11/18/13 Louis Talman
11/21/13 Robert Hansen
11/21/13 Louis Talman
11/16/13 Pam
11/16/13 Robert Hansen
11/16/13 Pam
11/16/13 Robert Hansen
11/18/13 GS Chandy
11/17/13 GS Chandy
11/17/13 Pam
11/17/13 Robert Hansen
11/17/13 Pam
11/17/13 Robert Hansen
11/17/13 Pam
11/18/13 Robert Hansen
11/18/13 Robert Hansen
11/18/13 Pam
11/18/13 Robert Hansen
11/25/13 Bishop, Wayne
11/25/13 Robert Hansen
11/22/13 Joe Niederberger
11/25/13 Bishop, Wayne
11/23/13 GS Chandy
11/24/13 Robert Hansen
11/25/13 Bishop, Wayne