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Simplifying Surds

  • Thread starter V-Tec
  • Start date
3
0
Ok here is my problem, I am not sure how to simplify surds with additions and subtractions in them such as ones like this:

http://img212.imageshack.us/img212/474/math010iz.gif [Broken]

At the moment I have managed to simplify it to this:

http://img212.imageshack.us/img212/2011/math026eg.gif [Broken]

However it is not simplified as possible, can someone give me some words of wisdom? Any help greatly appreciated!
 
Last edited by a moderator:

Answers and Replies

EnumaElish
Science Advisor
Homework Helper
2,285
123
In this case, 80 = 4 x 20, so [itex]\sqrt{80}=\sqrt 4 \times\sqrt {20}=2\sqrt {20}[/itex].

Therefore [itex]\sqrt{20}+\sqrt{80}= (1+2)\sqrt{20}=3\sqrt{20}[/itex], which is [itex]3\times 2\times\sqrt 5 = 6\sqrt 5[/itex].
 

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