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Simple C1 Co-ordinate Geometry Question - Help! watch

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    I'm using the distance formula, I'm confused where the square root of 1+4 came from. Can someone help?
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    post the question
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    (Original post by Tom__)
    post the question
    Its part (iii)
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    (Original post by Jessinoch)
    I'm using the distance formula, I'm confused where the square root of 1+4 came from. Can someone help?
    Did the question specify what form the answer should be in?
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    If you know where the sqrt49/4 + 49 comes from, the entire thing has just been divided by 12.25 (or 49/4)
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    (Original post by Fractite)
    If you know where the sqrt49/4 + 49 comes from, the entire thing has just been divided by 12.25 (or 49/4)
    But how do you get 7/2 on the outside of the square root?
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    are you sure you did the previous parts of the question correctly? I got a different answer to you
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    (Original post by Speedbird129)
    But how do you get 7/2 on the outside of the square root?
    The square root of 12.25 is 3.5, so you use that I think.
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    Surely it would be easier to just do square root of 49/4 + 49 and add them to get square root 61.25. This therefore equals 7 square root 5 divided by 2 which is the same answer??
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    (Original post by Tom__)
    are you sure you did the previous parts of the question correctly? I got a different answer to you
    Yeah, this is from physicsandmathstutor.com
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    (Original post by Speedbird129)
    Surely it would be easier to just do square root of 49/4 + 49 and add them to get square root 61.25. This therefore equals 7 square root 5 divided by 2 which is the same answer??
    Yeah but this is C1 so you can't use a calculator
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    (Original post by Speedbird129)
    Did the question specify what form the answer should be in?
    it said in surd form
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    All they've done is simplify.  \displaystyle \sqrt{\frac{49}{4}+49}\equiv \sqrt{\frac{49}{4}\left (1+4 \right )}\equiv \left (\frac{49}{4} \right )^{\frac{1}{2}}\sqrt{1+4} .
    So going one step further the answer is  \displaystyle \frac{7}{2} \sqrt{5} .
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    (Original post by Jessinoch)
    I'm using the distance formula, I'm confused where the square root of 1+4 came from. Can someone help?
    I assume you know how you get to \sqrt{\frac{49}{4}+49} at which point you know you can factor a 49 out of the expression under the square roots so you get \sqrt{49(\frac{1}{4}+1)} and then you can also factor out a quarter which gets you \sqrt{49\cdot \frac{1}{4}\cdot (1+4)} and then it's just the matter of splitting it into two square roots, one of which square roots nicely into a fraction.

    \sqrt{\frac{49}{4}} \cdot \sqrt{1+4}
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    (Original post by B_9710)
    All they've done is simplify.  \displaystyle \sqrt{\frac{49}{4}+49}\equiv \sqrt{\frac{49}{4}\left (1+4 \right )}\equiv \left (\frac{49}{4} \right )^{\frac{1}{2}}\sqrt{1+4} .
    So going one step further the answer is  \displaystyle \frac{7}{2} \sqrt{5} .
    Thankyou!
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    (Original post by RDKGames)
    I assume you know how you get to \sqrt{\frac{49}{4}+49} at which point you know you can factor a 49 out of the expression under the square roots so you get \sqrt{49(\frac{1}{4}+1)} and then you can also factor out a quarter which gets you \sqrt{49\cdot \frac{1}{4}\cdot (1+4)} and then it's just the matter of splitting it into two square roots, one of which square roots nicely into a fraction.

    \sqrt{\frac{49}{4}} \cdot \sqrt{1+4}
    Thankyou!
 
 
 

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