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    Hey guyss for Edexcel AS C1 and C2, do we need to know how to prove formulas and functions other than the formulas for sum of geometric and arithmatic sequences? If so please list the formulas we need to know how to prove! Thanks.
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    (Original post by ILOVEA-LEVELS)
    Hey guyss for Edexcel AS C1 and C2, do we need to know how to prove formulas and functions other than the formulas for sum of geometric and arithmatic sequences? If so please list the formulas we need to know how to prove! Thanks.
    I think you need to know how to prove the quadratic equation - it's in the textbook I think
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    (Original post by ILOVEA-LEVELS)
    Hey guyss for Edexcel AS C1 and C2, do we need to know how to prove formulas and functions other than the formulas for sum of geometric and arithmatic sequences? If so please list the formulas we need to know how to prove! Thanks.
    we should know how to prove the log rules too for C2
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    Here are the ones i know we need to know: (and i've also proved them just for revision)
    C1 Quadratic Equation Proof:
    ax^{2} + bx + c = 0
    complete the squareax^{2} + bx = -cx^{2} + \frac{b}{a}x = \frac{-c}{a}(x+ \frac{b}{2a})^{2} - \frac{b^{2}}{4a^{2}} = \frac{-c}{a}

(x+ \frac{b}{2a})^{2} = \frac{b^{2}}{4a^{2}} - \frac{c}{a}(x+ \frac{b}{2a})^{2} = \frac{b^{2}-4ac}{4a^{2}} 

(x+ \frac{b}{2a}) = \sqrt{\frac{b^{2}-4ac}{4a^{2}}}(x+ \frac{b}{2a}) = \frac{\sqrt{b^{2}-4ac}}{2a}x = \frac{\sqrt{b^{2}-4ac}}{2a} - \frac{b}{2a}x = \frac{-b \pm\sqrt{b^{2}-4ac}}{2a}

    C1 Sum of Arithmetic Series:
    S_{n} = a + (a+d) + (a+2d) + ... + (a+(n-2)d) + (a+(n-1)d)reverseS_{n} = (a+(n-1)d) + (a+(n-2)d) + ... + (a+2d) + (a+d) + aadd both2S_{n} = 2a + (n-1)d + 2a + (n-1)d + 2a + (n-1)d + ... + 2a + (n-1)d2S_{n} = n[2a + (n-1)d] S_{n} = \frac{n}{2}[2a + (n-1)d]

    C2 Sum of Geometric Series:
    S_{n} = a + ar + ar^{2} + ar^{3} + ... + ar^{n-2} + ar^{n-1}rS_{n} = ar + ar^{2} + ar^{3} + ar^{4} + ... + ar^{n-1} + ar^{n}  S_{n} - rS_{n} = a - ar^{n} S_{n}(1 - r) = a(1 - r^{n})S_{n} = \frac{a(1 - r^{n})}{(1 - r)}
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    (Original post by yasmin#2)
    Here are the ones i know we need to know: (and i've also proved them just for revision)
    C1 Quadratic Equation Proof:
    ax^{2} + bx + c = 0
    complete the squareax^{2} + bx = -cx^{2} + \frac{b}{a}x = \frac{-c}{a}(x+ \frac{b}{2a})^{2} - \frac{b^{2}}{4a^{2}} = \frac{-c}{a}

(x+ \frac{b}{2a})^{2} = \frac{b^{2}}{4a^{2}} - \frac{c}{a}(x+ \frac{b}{2a})^{2} = \frac{b^{2}-4ac}{4a^{2}} 

(x+ \frac{b}{2a}) = \sqrt{\frac{b^{2}-4ac}{4a^{2}}}(x+ \frac{b}{2a}) = \frac{\sqrt{b^{2}-4ac}}{2a}x = \frac{\sqrt{b^{2}-4ac}}{2a} - \frac{b}{2a}x = \frac{-b \pm\sqrt{b^{2}-4ac}}{2a}

    C1 Sum of Arithmetic Series:
    S_{n} = a + (a+d) + (a+2d) + ... + (a+(n-2)d) + (a+(n-1)d)reverseS_{n} = (a+(n-1)d) + (a+(n-2)d) + ... + (a+2d) + (a+d) + aadd both2S_{n} = 2a + (n-1)d + 2a + (n-1)d + 2a + (n-1)d + ... + 2a + (n-1)d2S_{n} = n[2a + (n-1)d] S_{n} = \frac{n}{2}[2a + (n-1)d]

    C2 Sum of Geometric Series:
    S_{n} = a + ar + ar^{2} + ar^{3} + ... + ar^{n-2} + ar^{n-1}rS_{n} = ar + ar^{2} + ar^{3} + ar^{4} + ... + ar^{n-1} + ar^{n}  S_{n} - rS_{n} = a - ar^{n} S_{n}(1 - r) = a(1 - r^{n})S_{n} = \frac{a(1 - r^{n})}{(1 - r)}
    I don't know whether it's a Latex issue or an algebra issue, but your proof of the quadratic formula makes no sense.
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    (Original post by tiny hobbit)
    I don't know whether it's a Latex issue or an algebra issue, but your proof of the quadratic formula makes no sense.
    youre right, this thing is so damn hard to use, i edited it like 3 times then gave up
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    (Original post by tiny hobbit)
    I don't know whether it's a Latex issue or an algebra issue, but your proof of the quadratic formula makes no sense.
    Hey Yasmin, how can you be sure that these are all the formulas that we need to know for the exam? How exactly did you find out?
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    (Original post by yasmin#2)
    Here are the ones i know we need to know: (and i've also proved them just for revision)
    C1 Quadratic Equation Proof:
    ax^{2} + bx + c = 0
    complete the squareax^{2} + bx = -cx^{2} + \frac{b}{a}x = \frac{-c}{a}(x+ \frac{b}{2a})^{2} - \frac{b^{2}}{4a^{2}} = \frac{-c}{a}

(x+ \frac{b}{2a})^{2} = \frac{b^{2}}{4a^{2}} - \frac{c}{a}(x+ \frac{b}{2a})^{2} = \frac{b^{2}-4ac}{4a^{2}} 

(x+ \frac{b}{2a}) = \sqrt{\frac{b^{2}-4ac}{4a^{2}}}(x+ \frac{b}{2a}) = \frac{\sqrt{b^{2}-4ac}}{2a}x = \frac{\sqrt{b^{2}-4ac}}{2a} - \frac{b}{2a}x = \frac{-b \pm\sqrt{b^{2}-4ac}}{2a}

    C1 Sum of Arithmetic Series:
    S_{n} = a + (a+d) + (a+2d) + ... + (a+(n-2)d) + (a+(n-1)d)reverseS_{n} = (a+(n-1)d) + (a+(n-2)d) + ... + (a+2d) + (a+d) + aadd both2S_{n} = 2a + (n-1)d + 2a + (n-1)d + 2a + (n-1)d + ... + 2a + (n-1)d2S_{n} = n[2a + (n-1)d] S_{n} = \frac{n}{2}[2a + (n-1)d]

    C2 Sum of Geometric Series:
    S_{n} = a + ar + ar^{2} + ar^{3} + ... + ar^{n-2} + ar^{n-1}rS_{n} = ar + ar^{2} + ar^{3} + ar^{4} + ... + ar^{n-1} + ar^{n}  S_{n} - rS_{n} = a - ar^{n} S_{n}(1 - r) = a(1 - r^{n})S_{n} = \frac{a(1 - r^{n})}{(1 - r)}
    1. Hey Yasmin, how can you be sure that these are all the formulas that we need to know for the exam? How exactly did you find out?
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    (Original post by ILOVEA-LEVELS)
    1. Hey Yasmin, how can you be sure that these are all the formulas that we need to know for the exam? How exactly did you find out?
    it says in the spec that the proof for the sum of arithmetic sequences and geometric should be known
    in the C1 book they put the proof for the quadratic formula so its better if you learn it incase youre asked to derive it with the assumption that you can complete the square
    the C2 book also shows the log rules and cosine rule proof
    (sorry the quadratic formula one looks really messy on here )
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    (Original post by ILOVEA-LEVELS)
    Hey guyss for Edexcel AS C1 and C2, do we need to know how to prove formulas and functions other than the formulas for sum of geometric and arithmatic sequences? If so please list the formulas we need to know how to prove! Thanks.
    If you look up the formulae and functions that you think might need proving in the textbook, if you look at the header (eg 8.6 - You must know .... 9.2 - You must be able to prove that ...) will give you an idea of how much you need to know. Sometimes it says in the orange boxes that you don't need to prove it in the exam.
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    (Original post by SeanFM)
    If you look up the formulae and functions that you think might need proving in the textbook, if you look at the header (eg 8.6 - You must know .... 9.2 - You must be able to prove that ...) will give you an idea of how much you need to know. Sometimes it says in the orange boxes that you don't need to prove it in the exam.
    as per what you've come across, what all needs proving?
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    (Original post by ILOVEA-LEVELS)
    as per what you've come across, what all needs proving?
    I've just looked at the specification and the only proof mentioned that must be known is the geometric series sum one.
 
 
 
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