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    They are the extreme values, both give volume of 0. Why allow one and not the other?
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    ok guys what proofs do we need to learn?
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    (Original post by TheWolf)
    ok guys what proofs do we need to learn?
    Only sum of geometric and arithmetic series, which I put at the start of this.

    Most other proofs revolve around the discriminant.
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    (Original post by mik1a)
    Only sum of geometric and arithmetic series, which I put at the start of this.

    Most other proofs revolve around the discriminant.
    ahh ok! cheers - we need to know the completing the square formulas too? ive never used it in my life before - and still get through all of the p1 past papers :confused:
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    (Original post by TheWolf)
    ahh ok! cheers - we need to know the completing the square formulas too? ive never used it in my life before - and still get through all of the p1 past papers :confused:
    My teacher says we do... never seen it myself either. :confused:
    I'd learn it just in case, it's not that hard and it's good practice for complicated completing the square...
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    (Original post by mik1a)
    My teacher says we do... never seen it myself either. :confused:
    I'd learn it just in case, it's not that hard and it's good practice for complicated completing the square...
    yea! thanks! i actually dont know what to revise for p1 now, more past papers? but theyre all the same, learn the formulas thats it. Id actually revise some economics, but i feel the need to revise for p1 cus its in 2 days time :confused:
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    (Original post by TheWolf)
    yea! thanks! i actually dont know what to revise for p1 now, more past papers? but theyre all the same, learn the formulas thats it. Id actually revise some economics, but i feel the need to revise for p1 cus its in 2 days time :confused:
    I'm not doing any, apart from answering questions. On the wednesday morning I'll probably do 3 past papers in the library to get me in the mood... but that's about it. I need to focus a LOT more on my economics - the housing paper is still impossible to answer. I haven't seen a housing question that I can answer worth all the marks! But I don't have a clue what to say when asked some weird 10 marker like "explain the effects of oppurtinuty cost on the housing sector"... WTF?"!
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    (Original post by mik1a)
    I'm not doing any, apart from answering questions. On the wednesday morning I'll probably do 3 past papers in the library to get me in the mood... but that's about it. I need to focus a LOT more on my economics - the housing paper is still impossible to answer. I haven't seen a housing question that I can answer worth all the marks! But I don't have a clue what to say when asked some weird 10 marker like "explain the effects of oppurtinuty cost on the housing sector"... WTF?"!
    yes housing - ****, micro will be ok, i need to revise macro + housing/environment ahhhhhhhhhhhhh
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    (Original post by deianra)
    I've seen it in a book of sample papers. Our teacher issued us with a book of ten papers for M1 and P1. Not sure where she got it from, but full mark schemes, very good help.

    I normally go through this lot first before going onto the proper past papers, thus I've only done 4 true past papers. Learn it, Wolfie. You might regret it otherwise
    Maybe she gave you the Delphis papers? Ours came in sets of 10 as well.
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    Thought I'd help people revise aswell as myself, this came up on Paper F i think from solomon. Proove that the solutions to the equation ax² + bx + c = 0 are given by:
    x = -b ±√(b² - 4ac)
    ----------------
    2a

    ax² + bx + c = 0
    a[x² + (b/a)x + (c/a)] = 0 {dividing equation by a, then adding a to the outside of the [] bracket's}
    a[(x + b/2a)² - (b²/(2a)²) + (c/a)] = 0 {complete the square}
    a[(x + b/2a)² - b²/4a² + c/a)] = 0
    a(x + b/2a)² - b²/4a + c = 0
    a(x + b/2a)² = b²/4a - c
    (x + b/2a)² = b²/4a² - c/a {divide equation by a}
    x + b/2a = ±√((b² - 4ac) / 4a²) {square root each side}
    x + b/2a = ±√(b² - 4ac) / 2a {sqrt 4a² (the bottom of the fraction and remove from withing the square root}
    x = -b/2a ±√(b² - 4ac) / 2a {take b/2a from both sides}
    x = -b ±√(b² - 4ac) {both fractions are divided by 2a so join the 2 fractions into one}
    ----------------
    2a

    the forums removes the spacing, dunno how to stop it so the final wquation looks funny. the 2a and ------------- should be below the right hand sode of the equation.

    (Original post by deianra)
    A/S Mathematics : P1. It says Solomon Press?

    Here's the question:

    (a) By completing the square, show that ax^2 + bx + c can be written as

    a(x + b/2a)^2 + c - b^2/4a

    (3 marks)
    Look at my post, follow it down to the 4/5th line.
    (Original post by deianra)
    (b) Hence prove that solutions of the equation ax^2 + bx + c=0 are given by


    x = -b...yada yada quadratic formula.

    (4 marks)
    from the 5th line watch how i get to the general quadratic equation. Hope you understand :x
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    anyone know where i can get answers for the solomon papers\?
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    That is a horrible way to prove the quadratic formula.

    An easier way:

    ax² + bx + c = 0 [quadratic in x]
    4a²x² + 4abx + 4ac = 0 [multiply by 4a]
    4a²x² + 4abx + b² - b² + 4ac = 0 [add and subtract b²]
    4a²x² + 4abx + b² = b² - 4ac [rearrange]
    (2ax + b)² = b² - 4ac [factorise]
    2ax = -b±√b² - 4ac [take the square root and rearrange]
    x = (-b±√b² - 4ac) ÷ 2a [QED]
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    mm, never seen it done like that before - its pretty nifty , but the question was 2 parts i just put missed out part a which was prove to get from start to line 5 then part b was prove from line 5 to end.
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    ok the syllabus says eg prove x^2=px=q=0 has distinct real roots if, and only if, p^2>4q.

    what shall i do?

    also how do you find increasing,decreasing functions?
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    (Original post by chats)
    ok the syllabus says eg prove x^2=px=q=0 has distinct real roots if, and only if, p^2>4q.

    what shall i do?

    also how do you find increasing,decreasing functions?

    For the latter you differentiate twice, not once, after you have found the co-ords of where the gradient=0 then sub them into the equation. If its a negative number it means its a decreasing function, i.e. gradient at that point is a maximum, and vice versa.
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    (Original post by mik1a)
    SHould that not be:

    |PQ| = [ (Y2-Y1)^2 + (X2-X1)^2 ]^1/2
    yes, sorry, my mistake!

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    what's the best calculator that can be used in P1 and P2? can you tell me make and model? i need to buy one
    are we allowed one which does quadratic formula? :rolleyes:
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    (Original post by SkylineGTR)
    what's the best calculator that can be used in P1 and P2? can you tell me make and model? i need to buy one
    are we allowed one which does quadratic formula? :rolleyes:
    The Sharp calculators, (the one with the solar panel), which is white with a dark blue cover. Cost you about £10, but is a very decent one.
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    i live in italy hope i'll find it, if you could tell me the model it would be perfect! thanks!
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    (Original post by SkylineGTR)
    i live in italy hope i'll find it, if you could tell me the model it would be perfect! thanks!
    Sharp EL-520V
 
 
 
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