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    (Original post by z_o_e)
    I need an introduction haha I know a bit of this
    :awesome:

    Just expand the brackets as you would with normal algebra.

    The final answer for the first one is 18+6√5


    The rules for surds have already been posted above, try the other questions out.

    I'll do the last one which involves rationalising the denominator.

    Edit: my answer is slightly wrong I wrote 3√5 instead of 6√5
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    (Original post by B_9710)
    There are very simple rules you need to follow to answer all of these questions.
     \sqrt a \times \sqrt b = \sqrt{ab} and also
     \displaystyle \frac{\sqrt a}{\sqrt b }= \sqrt{\frac{a}{b}} .
    Your messages come in different forms latex? I'm using my phone for tsr x

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    (Original post by z_o_e)
    Your messages come in different forms latex? I'm using my phone for tsr x

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    (Original post by 34908seikj)
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    Where did you get this 9=3 from?



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    (Original post by z_o_e)
    Where did you get this 9=3 from?



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    √9 = 3

    What's 3^2 ? It's 9. So therefore √9 = 3
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    (Original post by 34908seikj)
    √9 = 3

    What's 3^2 ? It's 9. So therefore √9 = 3
    OOOH. SO THIS IS SQUARE ROOT??
    Ohh

    And I didn't understand what I do after this..



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    (Original post by z_o_e)
    OOOH. SO THIS IS SQUARE ROOT??
    Ohh

    And I didn't understand what I do after this..



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    Multiply. Remember if you multiply the same two numbers together it's equivalent to squaring them. Since you're multiplying a square root number by the same square root number, the square root cancels out and you're just left with the number

    e.g. √3*√3 = 3 - or you can think of it like √3*√3 = √9 and √9 = 3


    √3 * √15 = √45 since it's just 3*15 under a root. Then you can simply the √45
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    (Original post by 34908seikj)
    Multiply. Remember if you multiply the same two numbers together it's equivalent to squaring them. Since you're multiplying a square root number by the same square root number, the square root cancels out and you're just left with the number

    e.g. √3*√3 = 3 - or you can think of it like √3*√3 = √9 and √9 = 3


    √3 * √15 = √45 since it's just 3*15 under a root. Then you can simply the √45
    Do I simplify 90?

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    (Original post by z_o_e)
    Do I simplify 90?

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    No, you have two pairs of √45 so it would be 2√45, not √90, you CAN'T add surds like that.
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    (Original post by 34908seikj)
    No, you have two pairs of √45 so it would be 2√45, not √90, you CAN'T add surds like that.
    Can you do this part please?

    On paper and shown it out please x

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    Anyone needs help!!Ask me,I am here to help you guys.
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    (Original post by z_o_e)
    Can you do this part please?

    On paper and shown it out please x

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    So you have 3 + √45 + √45 + 15


    : 18 + 2√45


    √45 Simplifies down to 3√5

    So now you have 18 + (2)(3)√5

    Which gives you the final answer of 18 + 6√5
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    (Original post by 34908seikj)
    So you have 3 + √45 + √45 + 15


    : 18 + 2√45


    √45 Simplifies down to 3√5

    So now you have 18 + (2)(3)√5

    Which gives you the final answer of 18 + 6√5
    GOT IT !!!



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    (Original post by z_o_e)
    GOT IT !!!



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    Yup! Try the other question by yourself now, see how far you get.
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    (Original post by 34908seikj)
    Yup! Try the other question by yourself now, see how far you get.
    I think I should learn to do these ones then move onto rationalalizing?



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    (Original post by z_o_e)
    I think I should learn to do these ones then move onto rationalalizing?



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    That's right. Rationalising is really straight forward, so yes I think you should
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    (Original post by 34908seikj)
    That's right. Rationalising is really straight forward, so yes I think you should
    I'll do one last question on this without looking back at my notes xx

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    (Original post by 34908seikj)
    That's right. Rationalising is really straight forward, so yes I think you should


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    I get 54+24√2


    You've messed up for working out slightly; you write + for everything when some of the sums should have been multiplied.
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    (Original post by 34908seikj)
    I get 54+24√2


    You've messed up for working out slightly; you write + for everything when some of the sums should have been multiplied.
    I corrected them in red pen.


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