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    Hey guys. I feel a little embarrassed asking this, but could anyone help me in simplifying this surd:

    20√2 / √5

    Someone take me step by step through this so I get to 4√10
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    (Original post by James A)
    Hey guys. I feel a little embarrassed asking this, but could anyone help me in simplifying this surd:

    20√2 / √5

    Someone take me step by step through this so I get to 4√10
    Rationalise the denominator.
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    What do you do when you have a surd as the denominator? Is this really C2?

    Edit: ^The guy beat me to it.
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    Times the numerator and the dominator by root 5


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    Not sure I'm a GCSE student but ill give it a go. So
    20√2 / √5

    First times by
    √5/√5 so you get 20√2√5 over 5. Then √2 x √5 = √10 so now you have 20√10 over √5 x √5 which = 5. So 20√10 / 5 . Then divide by 5 to get 4√10
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    (Original post by usycool1)
    Rationalise the denominator.

    (Original post by QuantumSuicide)
    What do you do when you have a surd as the denominator? Is this really C2?

    Edit: ^The guy beat me to it.

    Well I'm retaking C2 for the first time. Last time I took this exam was back in june 11. Also, this was part of a trig question, and rather than using my calc to work out the surds, I thought it would be more practical to figure out why exactly the answer is 4√10.

    Also, first time I've touched A-level maths since C4 last june!

    (Original post by nadinelia11)
    Times the numerator and the dominator by root 5


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    Just to clarify to all, I do (20√5 * √5) / (√5 * √5)

    ?
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    (Original post by James A)
    Just to clarify to all, I do (20√5 * √5) / (√5 * √5)

    ?
    It should be 20√2 (I presume that was a typo).

    But yes, you have the right idea.
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    (Original post by usycool1)
    It should be 20√2 (I presume that was a typo).

    But yes, you have the right idea.
    :teehee:

    I understand now :yep:
 
 
 
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