Two Unknowns

Posted on September 12, 2014

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Our pre-algebra course Only Uses One Variable, thank you, …

… students are confronted with the infamous “PersonA is 3 older than PersonB.  The sum of their ages is 50”  … with a few more words and obfuscations…

PersonA                 +                 Person B   = 50.

Okay.   If they were the same age, I could just say
x + x = 50

and divide by two.

Why can’t I do that?   (hmmm….)

So!   I have my one x for PersonB… now (and we figure out from the problem how to represent the modified dude with algebra, which they have been learning).

It seems to make it a *little* easier to keep from just doign the one operation starting with “if they were the same it would be x + x.”

The other example is with hamburgers and cheeseburgers… and that is a little eaiser because I can say “but where are the hamburgers?”  and actually draw stacks of ’em…

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Posted in: word problems