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Square Roots

  1. Sep 12, 2007 #1
    Hi i have just started A lvel maths and we are doing surds, i was never taught this in secondary school so i am at a complete loss.

    I have barly understood the basics but struggled when having to simplify equations Such as (3 + √2) + (5 + 2√2)


    I know the answer is 8 + 3√2 but can not find any way to solve it as my way to get the answer goes against math rules.

    Please if you tell me how to work this one out i can do the other 14 by my self.

    Thanks in advance.
     
  2. jcsd
  3. Sep 12, 2007 #2

    learningphysics

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    Treat the √2 the same way you would a simple algebraic variable... How would you simplify this:

    (3 + x) + (5 + 2x)
     
  4. Sep 12, 2007 #3

    Dick

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    Use the associative law to regroup as (3+5)+(sqrt(2)+2*sqrt(2)). You can probably handle 3+5 so for the surd part use the distributive law to write 1*sqrt(2)+2*sqrt(2) as (1+2)*sqrt(2).
     
  5. Sep 12, 2007 #4
    thanks dick i see that now. so this one (5 +3√2) - (5 - 2√2) would (5-5) (2+3√2) so it would be 5√2

    is my math right?
     
  6. Sep 12, 2007 #5

    learningphysics

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    The answer is right, but you should write this part "(5-5) (2+3√2)" as: (5-5) + (2√2+3√2) or maybe this is what you meant which is also right: (5-5) + (2+3)√2
     
    Last edited: Sep 12, 2007
  7. Sep 12, 2007 #6
    yeah thats what i meant thanks for your help.
     
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