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OCR Core 2 - 22nd May

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Reply 80

Ejit

someperson

i did this question in the last 2minutes and wasnt sure if i did it right!

Did you get some obscure decimal for one of them? I don't remember if it was C or A, but I did, and substituted it back into the others and it seemed right.

Reply 81

Pretence

blap

It went really well for me.
I got k to be 9, did anyone else get that?

yeah k=9 ....

omg i cant believe i fluffed the 8 mark question! i intergrated the equation wrongly so i got x^3 + a^2/2 +c ....but then i started putting in the values of the coordinates and started to do simultaneous equations ( but obviously that didnt work) - does any1 think i mite be able 2 scrounge a few marks?

Reply 82

Tomyuri

the second trig was fun :smile:

i dont know what a factor therom is though :frown:

Reply 83

Andylol

For the Trapezium question, I got sqrt k as 3 or 5, so k must be 9 or 25. But when I subbed it into the equation it only worked for 9 and not 25, so it had to be 9 :smile:

Also, that 3rd question was solid (

7^x = 2^{x+1}

)! I used so many methods to work it out but still got x as 1.81 - which is completely wrong, that was some shizz!

Reply 84

someperson

Ejit

Did you get some obscure decimal for one of them? I don't remember if it was C or A, but I did, and substituted it back into the others and it seemed right.

not sure ...actually i think i remember getting some fraction but didnt have enough time to put it in and check.

what did everyone else get?

Reply 85

dannycarr1

Ejit

I did:
integrate to find y.
substitute in the co-ordinates given as y=mx+c, and make a simultaneous equation to find A and C.

I integrated to find y..

so got x^3 + ax ..
then y=mx+c

but then when i put in the different equations it didnt seem to work.. i came out with different values when i substituted (2, 17) and (-1, 2) into it..
Oh well.. 3 or 4 method marks if im lucky :rolleyes:

Reply 86

Graham22

im an A student and i found that exam much harder than any of the past papers i have done..there quite a few tough questions but the rest was alright

Reply 87

LiamSwainy

Ejit

I did:
integrate to find y.
substitute in the co-ordinates given as y=mx+c, and make a simultaneous equation to find A and C.

Ditto.

Reply 88

Graham22

what did everyone get for the arithmetic progression one..just to see if i may have a few marks in the bag
I got a=6 and d=2

Reply 89

Tomyuri

Graham22

im an A student and i found that exam much harder than any of the past papers i have done..there quite a few tough questions but the rest was alright

that makes me happy. :woo:

Reply 90

dannycarr1

Graham22

what did everyone get for the arithmetic progression one..just to see if i may have a few marks in the bag
I got a=6 and d=2

Correct..

because
a + 9d = 2(a+3d)
a + 9d = 2a + 6d
a = 3d

a + 19d = 44
3d + 19d = 44
22d = 44
d = 2

a + 19d = 44
a + 38 = 44
a = 6

Reply 91

Haruhi

2sin^2x = 2- (root 3)cosx

you use the identity sin^2x + cos^2x = 1 to find sin^2x
sin^2x = 1 - cos^2x

you substitute this into the equation to turn it all to cos x

so

2(1-cos^2x) = 2 - (root 3)cos x
2-2cos^2x = 2 - (root 3)cos x

get all the cos x on one side and numbers on the other side.

(root 3)cosx + 2cos^2x = 0

let cosx = Y

2(y^2) + root3 (Y) = 0

a = 2 b=root3 c=0

-root3 +- squareroot of (3-0) all divided by 4

-root3 + root3 all over 4 = 0
-root3 - root3 all over 4 = - root3 / 2

cos-1 0 = 90
cos-1 -root3 / 2 = 150

OMG I JUST PROVED MYSELF WRONG O__O. I am such an idiot! >< I probably punched in the wrong numbers T__T

Reply 92

Andylol

I wonder if Mr M will post the answers for this later :smile:

Reply 93

Pretence

does any1 remember what they got for the sum of the first 50 terms ? ( 2nd part of that question - a= 6, d=2 )

Reply 94

Maximald

Andylol

I wonder if Mr M will post the answers for this later :smile:

I really hope so :p:

Reply 95

QED

I'm pretty certain I got everything except the second solution to 5 part ii. Much happier with that paper than C1, which I fluffed so bad.

Reply 96

Ejit

Graham22

what did everyone get for the arithmetic progression one..just to see if i may have a few marks in the bag
I got a=6 and d=2

same.

I <3 Mr. M, if he hadn't sent me the Jan 2009 paper I would have failed.

For the sector geometric progression, was it that it would never exceed 150, because the power would never evaluate to 0 or less? And the S of the first whatever was around 149. something?

Reply 97

QED

Pretence

does any1 remember what they got for the sum of the first 50 terms ? ( 2nd part of that question - a= 6, d=2 )

2600.

Reply 98

definite_maybe

QED

2600.

I got something like 2750.

Reply 99

Graham22

Tomyuri

the second trig was fun :smile:

i dont know what a factor therom is though :frown:

factor theorem is the remainder and quotient thing
the exam question asked to show that (2x-1) was a factor...all you have to do for that is sub in x=1/2 into f(x) and the answer should come out as 0. thats all that factor theorem is