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    x^2+10x+17
    Solve the equation giving your answer to 3 significant figures.
    This question is in c1 so you can't use a calculator for this question.
    Could anyone talk me through how to solve it?
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    I would complete the square. The mental arithmetic involved should look easier that way than diving straight in with the quadratic formula.
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    I would disagree, every time you see correct your answer to 3 significant figures you have to use the quadratic formula
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    (Original post by kalvin689)
    I would disagree, every time you see correct your answer to 3 significant figures you have to use the quadratic formula
    Well, the quadratic formula is derived from completing the square, so they are effectively the same thing. But I have to confess that I didn't notice the 3 s.f. bit, which seems worrying for a C1 question, unless it comes out very nicely.
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    Having just had a try, there is no way that this can be done to 3 s.f. without a calculator, unless there is more information at the start of the question that we don't have.
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    (Original post by Pangol)
    Well, the quadratic formula is derived from completing the square, so they are effectively the same thing. But I have to confess that I didn't notice the 3 s.f. bit, which seems worrying for a C1 question, unless it comes out very nicely.
    Good point, but I believe this is still a very standard and easy C1 question
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    This is all the information provided
    10)a) is the question btw


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    (Original post by Vinni0001)
    This is all the information provided
    10)a) is the question btw


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    Which textbook is this from?
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    Oops sorry guys, I forgot C1 was non-calc.. It's been a while.
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    I can only assume that you are allowed to use a calculator for this question in the text book, even though you can't in an exam. Perhaps it's adding some extra context, such as when you'll need the same method in C2-C4.
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    Core mathematics 1 edexcel AS and A level modular mathematics from pearsons is the book im using

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    i think at the beginning of the exercise it says only for this exercise you can use the calculator.

    I'd still try and get an exact answer from the formula or completing the square regardless, good practise especially the latter. i forget how to do it too often and it helps so often in C3 onwards
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    (Original post by Vinni0001)
    Core mathematics 1 edexcel AS and A level modular mathematics from pearsons is the book im using

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    Ah yes these questions are from the review exercise.

    You're meant to use a calculator for these questions. They shouldn't be part of the C1 textbook and you would of course never see a question like this in a C1 exam.
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    Coolio, thanks

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