Maths year 11

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    (Original post by RDKGames)
    You got the part with 2\sqrt{45} + 18 right and you know that \sqrt{45}=3\sqrt5 from what you've shown. You can use this replace the \sqrt{45} in the original answer.
    What shall I do after?

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    (Original post by z_o_e)
    What shall I do after?

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    You should really stop asking so much step-by-step otherwise I'm the one doing the question for you. I mean what's the obvious thing to do when you have 2(3\sqrt5)+18...?
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    (Original post by RDKGames)
    You should really stop asking so much step-by-step otherwise I'm the one doing the question for you. I mean what's the obvious thing to do when you have 2(3\sqrt5)+18...?
    Yeah it just I want to do one step by step with you so I can practise other questions on my own. I picked out the difficult ones. And I'm doing them but I get stuck.
    Just got 2 left then ill stop

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    (Original post by RDKGames)
    You should really stop asking so much step-by-step otherwise I'm the one doing the question for you. I mean what's the obvious thing to do when you have 2(3\sqrt5)+18...?
    I got 18 + 6 root 5

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    (Original post by z_o_e)
    I got 18 + 6 root 5

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    Yeppppp
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    (Original post by RDKGames)
    Yeppppp
    Sorry if you're annoyed. But I never did a question like this before.


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    (Original post by z_o_e)
    Sorry if you're annoyed. But I never did a question like this before.


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    Correct. You know what root 4 is so you can replace that and you're done.
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    (Original post by RDKGames)
    Correct. You know what root 4 is so you can replace that and you're done.
    So it's5 root 2 / 2?


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    (Original post by z_o_e)
    So it's5 root 2 / 2?


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    Yes
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    (Original post by RDKGames)
    Yes
    Thank you

    And I didn't understand this one .

    Like I Multiplied it by a positive and negative surd.


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    (Original post by z_o_e)
    Thank you

    And I didn't understand this one .

    Like I Multiplied it by a positive and negative surd.


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    You don't understand it because you've done the method wrong. What you've done is assuming that (a+b)(a+b)=a^2+b^2 which is plain wrong.

    Multiply out the brackets.
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    (Original post by RDKGames)
    You don't understand it because you've done the method wrong. What you've done is assuming that (a+b)(a+b)=a^2+b^2 which is plain wrong.

    Multiply out the brackets.
    What is this type of a question called I'll research a method.

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    (Original post by z_o_e)
    What is this type of a question called I'll research a method.

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    Just rationalising the denominator with 2 terms. http://www.mesacc.edu/~scotz47781/ma...m_2_terms.html
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    (Original post by RDKGames)
    Just rationalising the denominator with 2 terms. http://www.mesacc.edu/~scotz47781/ma...m_2_terms.html
    How's this?


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    (Original post by z_o_e)
    How's this?


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    Should be  \displaystyle \frac{2-\sqrt 3 }{2^2-(\sqrt 3)^2} .
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    (Original post by B_9710)
    Should be  \displaystyle \frac{2-\sqrt 3 }{2^2-(\sqrt 3)^2} .
    What about now?


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    (Original post by z_o_e)
    What about now?


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    Why did you completely ignore the denominator the change?
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    (Original post by RDKGames)
    Why did you completely ignore the denominator the change?
    What do you mean?

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    (Original post by z_o_e)
    What do you mean?

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    Denominator.

    (2+\sqrt3)(2-\sqrt3)\not=2^2-(\sqrt2)^2
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    (Original post by RDKGames)
    Denominator.

    (2+\sqrt3)(2-\sqrt3)\not=2^2-(\sqrt2)^2
    I don't understand this.

    Can you do this as one question as an example cause I've got others to do like similar ones.

    I started rationalising.



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