Top 10 Algebra Mistakes

Date: 05/23/98 at 21:03:41
From: Jesse
Subject: Top 10 algebra mistakes

Dear Dr. Math,

I am doing a survey and want to know what you think are the top 10 
mistakes that are made in algebra.

Thanks,
Jesse

Date: 05/24/98 at 18:07:00
From: Doctor Dawn
Subject: Re: Top 10 algebra mistakes

Hi Jesse,

This sounds like an interesting survey.  I'm actually curious to know 
what the other math doctors and other math teachers think.  My top ten 
list of algebra mistakes are

 1. Arithmetic errors
    (example:  2+3 does not = 6)

 2. Copy errors within the problem
    (such as forgetting to bring a negative sign down to the next 
    line)
 
 3. Forgetting to distribute the negative 
    2x * -4(3x-3) does not = 2x -12x-12

 4. Factoring out the negative incorrectly.
    -5y-15 does not = -5(y-3) 

 5. Reducing rational expressions by "canceling" incorrectly  

    4y + 8               8
    ------  does not =  ---
    4y + 3               3 

 6. Forgetting to distribute all terms when multiplying binomials
    (that is, forgetting the Outside and Inside terms when using the  
    FOIL method)
    (3y+2)(2y+1) does not = 6y^2 + 2

 7. Trying to factor the sum of squares.
    y^2 + 9 does not = y+3

 8. Forgetting "whatever you do to the left, you must do to the right"  
    when solving equations.

 9. In word problems, not clearly identifying and defining the 
    variable(s).

10. In word problems, not translating the English into the correct   
    "Math language."

Thanks for asking and good luck. 

Doctor Dawn,  The Math Forum
 http://mathforum.org/dr.math/   

Date: 05/24/98 at 18:08:47
From: Doctor Sonya
Subject: Re: Top 10 algebra mistakes

Hi Jessie. In addition to what Dr. Dawn wrote, I would add:

Not checking your work when you're done.

Have fun with your survey.

-Doctor Sonya,  The Math Forum
 http://mathforum.org/dr.math/   

Date: 05/24/98 at 19:56:36
From: Jesse Hodgson
Subject: Thanks

Thank you very much for responding to my question so quickly Dr. Dawn 
and Dr. Math.  You have been a big help!