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    Came across a question on definite integration and I'm not sure why it doesn't work

    "Use integration to find giving your answer in the form a+b√3, where a and b are constants to be determined."

    is what I got, and when subbing in √3 and 1, I get an answer as a long decimal instead of surd. Is there something wrong with the question or have I missed something?
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    (Original post by Rexx18)
    Came across a question on definite integration and I'm not sure why it doesn't work

    "Use integration to find giving your answer in the form a+b√3, where a and b are constants to be determined."

    is what I got, and when subbing in √3 and 1, I get an answer as a long decimal instead of surd. Is there something wrong with the question or have I missed something?
    Not sure how you can get a "long decimal" as the answer - you should be able to see just by looking at it that the answer's going to be a surd!

    Post some working, then someone can see where you've gone wrong
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    (Original post by Rexx18)
    Came across a question on definite integration and I'm not sure why it doesn't work

    "Use integration to find giving your answer in the form a+b√3, where a and b are constants to be determined."

    is what I got, and when subbing in √3 and 1, I get an answer as a long decimal instead of surd. Is there something wrong with the question or have I missed something?
    When you sub in the values, you get:

    \frac{(\sqrt{3})^4}{24} - \frac{1}{3\sqrt{3}} - \frac{1}{24} + \frac{1}{3 \times 1}

    Collect up all the rational parts, and note that \frac{1}{3\sqrt{3}} = \frac{1}{9} \cdot \sqrt{3}. I'm uncertain as to what your issue is? Are you using a calculator? If so, don't. Use your head.
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    (Original post by Rexx18)
    Came across a question on definite integration and I'm not sure why it doesn't work

    "Use integration to find giving your answer in the form a+b√3, where a and b are constants to be determined."

    is what I got, and when subbing in √3 and 1, I get an answer as a long decimal instead of surd. Is there something wrong with the question or have I missed something?
    .... You used your calculator didn't you? use some workings out for subbing in \sqrt 3
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    DId you use a calculator? I got 2/3 - 1/9 (root 3)
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    = 0.47422

    Yeah, I did use a calculator for it
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    (Original post by Rexx18)
    Came across a question on definite integration and I'm not sure why it doesn't work

    "Use integration to find giving your answer in the form a+b√3, where a and b are constants to be determined."

    is what I got, and when subbing in √3 and 1, I get an answer as a long decimal instead of surd. Is there something wrong with the question or have I missed something?
    Your integration is correct.

    You need to work it out manually I'm afraid. Your calculator will churn out a decimal if you put it all in. You may be able to calculate each individual term, but certainly not altogether.
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    Hmm, alright, this is the first def. integration question I've seen in which I can't use my calculator, thanks for the answers guys
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    (Original post by Rexx18)
    Hmm, alright, this is the first def. integration question I've seen in which I can't use my calculator, thanks for the answers guys
    What board are you doing? I am pretty sure you can't use your cacluator to integrate. You have to show your working. You can use the calc to add big integers/fractions but you generally you give answers in exact form.
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    Edexcel, I didn't mean I have one of those calculators that do integration for you, I meant that once you end up with the square brackets and limits, I sub in the limits into the equation all in one go to give me the answer, but in this case, it gave me a long decimal instead of the a+b√3 format
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    (Original post by Rexx18)
    Edexcel, I didn't mean I have one of those calculators that do integration for you, I meant that once you end up with the square brackets and limits, I sub in the limits into the equation all in one go to give me the answer, but in this case, it gave me a long decimal instead of the a+b√3 format
    But why would you do that when you can see just by looking that you're going to get a simple fraction plus a surd that's easy to rationalize?

    You've made more work for yourself when all you needed after the integration was a bit of GCSE-level manipulation
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    Probably just a habit I guess, I tend to type in whatever I need using the Ans button, whether it's definite integration, numerical solutions in FP1 or anything like that, I find it much faster. But I guess I'll work it out without a calculator if it asks for the answer in surd format
 
 
 
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