Maths year 11

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Four things that unis think matter more than league tables 08-12-2016
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    (Original post by z_o_e)
    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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    You can simplify q4 and q5 further.

    Example of the question (bottom part of the page):

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    (Original post by RDKGames)
    You can simplify q4 and q5 further.

    Example of the question (bottom part of the page):

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Size:  65.6 KB


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    Thank you so for 5 and 6 you mean the surd 6 can be simplified ?

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    (Original post by z_o_e)
    Thank you so for 5 and 6 you mean the surd 6 can be simplified ?

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    No that surd cannot be simplified any further. But the fact that you have terms of 12/6 and 4/2, those can be.
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    (Original post by RDKGames)
    No that surd cannot be simplified any further. But the fact that you have terms of 12/6 and 4/2, those can be.


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    2 things are wrong with that. First line: The denominator on the right side is wrong. Check it again closely. Second line: (\sqrt{5})^2+1^2 is not equal to 1.
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    Why are you dissecting root 6...? I said that you cannot simplify that any further.
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    (Original post by RDKGames)
    Why are you dissecting root 6...? I said that you cannot simplify that any further.
    Yeah I fixed this.


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    I don't get how in suppose to simplify the 4 and 6 as the have numbers in front of them too and inside them.

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    (Original post by z_o_e)
    Yeah I fixed this.


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    Well your answer is right because you've made two wrong's which cancel each other out. For the first line you still made the same mistake but with opposite sign now.
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    (Original post by RDKGames)
    Well your answer is right because you've made two wrong's which cancel each other out. For the first line you still made the same mistake but with opposite sign now.


    I give up.


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    (Original post by z_o_e)
    I give up.


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    The problem here is that it doesn't look like you know what you're doing and why you're doing it. Simply guessing hoping to get the right answer.
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    (Original post by RDKGames)
    The problem here is that it doesn't look like you know what you're doing and why you're doing it. Simply guessing hoping to get the right answer.
    But I looked at your example and followed it.


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    (Original post by z_o_e)
    But I looked at your example and followed it.


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    But do you understand the maths in it?
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    (Original post by RDKGames)
    But do you understand the maths in it?
    Yes

    Could you point out where the mistake was so I could fix it in green pen and not make that on the other questions. I'd rather keep on going cause I made it this far.

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    (Original post by z_o_e)
    Yes

    Could you point out where the mistake was so I could fix it in green pen and not make that on the other questions. I'd rather keep on going cause I made it this far.

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    Denominator after the equals sign on line 1: should be (\sqrt5 - 1)(\sqrt5 + 1). The rest is fine.

    If you understand it, explain to me why we multiply \frac{1}{\sqrt5 - 1} by \frac{\sqrt5 + 1}{\sqrt5 + 1} rather than \frac{\sqrt5 - 1}{\sqrt5 - 1} as you would initially guess.
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    (Original post by RDKGames)
    Denominator after the equals sign on line 1: should be (\sqrt5 - 1)(\sqrt5 + 1). The rest is fine.

    If you understand it, explain to me why we multiply \frac{1}{\sqrt5 - 1} by \frac{\sqrt5 + 1}{\sqrt5 + 1} rather than \frac{\sqrt5 - 1}{\sqrt5 - 1} as you would initially guess.
    Cause we do that rule (a+b) (a-b)

    And then do the double brackets and do the squares and work that out to find the denominator of the answer.

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    (Original post by z_o_e)
    Cause we do that rule (a+b) (a-b)

    And then do the double brackets and do the squares and work that out to find the denominator of the answer.

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    That's not the reason. What you've said applies to either case hence it's not the reason.

    What is important about (a+b)(a-b) is that it is the difference of two squares whereby (a+b)(a-b)=a2-b2. So when either a or b is a surd, it will always become an integer. The problem with (a+b)(a+b) is that it equals a2+b2+2ab and due to the 2ab term we would never rationalise the surds, hence never rationalise the denominator.
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    (Original post by RDKGames)
    That's not the reason. What you've said applies to either case hence it's not the reason.

    What is important about (a+b)(a-b) is that it is the difference of two squares whereby (a+b)(a-b)=a2-b2. So when either a or b is a surd, it will always become an integer. The problem with (a+b)(a+b) is that it equals a2+b2+2ab and due to the 2ab term we would never rationalise the surds, hence never rationalise the denominator.
    how did this go?


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    (Original post by z_o_e)
    how did this go?


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    Numerator's incorrect.
 
 
 
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