Help with proof or equation for daughter's algebra teacher

krissi772 · 2017-01-18 14:14:11

It has been a long time since I took Trig, Algebra, Geometry, or Calculus. Always loved math, but I teach Kindergarten now so basically 2+2 is the hardest problem I've had to solve in awhile.

My 13 year old daughter is in 8th grade. Her Algebra teacher recently changed seating arrangements. My daughter wants to sit with her last math partner, and, since he is a great influence & incredibly helpful to her in math, I am supporting her with this. Problem is, her Algebra teacher will only move her back beside her old partner if she can come up with a mathematical proof or equation proving why she should be allowed to sit beside him. The teacher said the more creative the better. A search of "fun math proofs" or "math proofs about life" essentially only yields the old "Women are the root of all evil" proof, and I am having a hard time getting inspired with that.

Any ideas? I thought about adding the letters of their names & figuring out some way to put them in an equation or figuring out a way to show the two should be adjacent with a shape or an angle. I just can't get inspired...
Help would be greatly appreciated.

bobbym · 2017-01-18 22:22:49

The "Women are the root of all evil proof?" I never heard of that one. I thought money was the root of all evil. Did they change it? Darn mathematicians, I hate em. Always changing things on you while you are sleeping.

I was watching this movie yesterday call "Bad Teacher" with Cameron Diaz. The best way to get her to do what they wanted was to have the parents give her some cash. The equation cash + Mo cash = buku-bucks seemed to work. Or maybe you can try some intimidation: get someone really big and have him point out to the teacher that right crosses and left hooks are often more effective when delivered with the assistance of gravity. You could use trig and some blasted physics to support that assertion.

Or, you could just say you know bobbym, that works for me when I want someone to do it my way. Welcome to the forum.

Her Algebra teacher recently changed seating arrangements

Teachers back in my day were not clever enough to arrage us in any other way then alphabetizing. I always was lucky enough to sit behind Rosemarym, the girl of my dreams. How did he come up with another seating arrangement?

Bob · 2017-01-18 22:31:20

hi krissi772

Welcome to the forum.

Here's my suggestion. I think it is Ok for a grade 8 student (I'm from the UK so I'm not so familiar with exactly what comes up when).

Imagine the seats have been numbered so that her ideal seat is x and his is y, where x+1 = y.

Then we need a standard algebra paradox. You'll find it in many maths texts.

Let a be any number and b so that a = b

Then

Cancelling the (a-b) factors ***

Since b was any number it could be:

So they are in adjacent seats!!!

*** I expect the teacher will want to quiz her some more about why this paradox is a 'cheat'.

The line that is illegal is the one marked ***

Cancelling a factor is the same as dividing by the factor. (a-b) = 0 and it is not allowed to divide by zero.

Here's why it is not allowed:

Anything times zero is always zero. So:

If you divide by zero you get 63 = 89 which is clearly not a good basis for a number system. To avoid this the definitions for the number system specify that you cannot divide by zero.

Hope that helps,

Bob

ps. If the teacher still won't cooperate your daughter does have a plan B. She can join MIF and get any help she wants here.

Math Is Fun Forum

#1 2017-01-18 14:14:11

Help with proof or equation for daughter's algebra teacher

#2 2017-01-18 22:22:49

Re: Help with proof or equation for daughter's algebra teacher

#3 2017-01-18 22:31:20

Re: Help with proof or equation for daughter's algebra teacher

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