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# P1 Revision topic - 1:15pm 9th June - Edexcel watch

1. They are the extreme values, both give volume of 0. Why allow one and not the other?
2. ok guys what proofs do we need to learn?
3. (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.
4. (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
5. (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
My teacher says we do... never seen it myself either.
I'd learn it just in case, it's not that hard and it's good practice for complicated completing the square...
6. (Original post by mik1a)
My teacher says we do... never seen it myself either.
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
7. (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
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?"!
8. (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
9. (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.
10. 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

(4 marks)
from the 5th line watch how i get to the general quadratic equation. Hope you understand :x
11. anyone know where i can get answers for the solomon papers\?
12. 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]
13. 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.
14. 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?
15. (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.
16. (Original post by mik1a)
SHould that not be:

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

17. 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?
18. (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?
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.
19. i live in italy hope i'll find it, if you could tell me the model it would be perfect! thanks!
20. (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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