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OCR (not MEI) C1 13/05/13

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today is getting better xD so far I reckon iv got 100ums if im lucky with the grade boundaries.

wat did u get for the question that said wat values of x is the curve decreasing?

X <1/4

Original post by StickySteve

It was to solve a quadratic, with x^6 + x^3 + (..) or something and a typical method would be to substitute a = x^3 or something, and rewrite it as a^2 + b + c

I got x = + - 1/2

and my other x value was cuberoot of -1 ? But i mistook that for a square root though X(

Ah I remember, I got 1/2 and -1.

(edited 10 years ago)

Reply 121

XiLE

Original post by StickySteve

Wasnt it just x = -1/2 & x = -1?
I thought y = -1/8 & y = -1 so you just cube root both values to get x which would be -1/2 & -1
Or did I miscalculate something. :s

K=-5
A=(-2,-27)

last question was -3,-27
k= -5
the paper in general was good i thought. The first surd was booooky tho lol

Reply 124

Newbie95

Original post by Jack_King

Question 10iii) For the coordinates of A, I set the line equal to the curve, and then equated it to 0, then solved it using the remainder theorem, to obtain a quadratic, solved the quadratic and got X to be -2, subbed X value into the curve and got Y to be -27. So the point = (-2,-27) Would I get 5/5 marks for this method?

I did the same thing as you but because I had my K as -4, I got completely different values. But that is a completely valid method I believe.

Reply 125

thebigman1

What did people get for question 8? (the other 7 marker)

Reply 126

GeorgeBarrett1

Original post by XiLE

Wasnt it just x = -1/2 & x = -1?
I thought y = -1/8 & y = -1 so you just cube root both values to get x which would be -1/2 & -1
Or did I miscalculate something. :s

I got the same, think its correct

Reply 127

a10

Original post by eggfriedrice

X <1/4

Ah I remember, I got 1/2 and -1.

1/4???? wer did u get that from I put

x>-3/2
x < 4

Reply 128

nikki_27

what do you think the minimum mark will be for an A?

Reply 129

Dugald

Original post by Lilhazzaman

First you say the dy/dx = -3x^2 ect.
Then you say dy/dx = 3x^2 ect.

I dont understand where the Negative has come from. Was the original equation; (x-1)(x^2+4x+k)?

yeah sorry, typing on phone.

dy/dx=-3x^2-6x+9

Reply 130

Bohla

fuuuuuuuccckk cube rt -1 is still -1, i was thinking of sqrt -1 giving no solution. well, i was bound to lose one mark

Reply 131

cheetahs56

Original post by Newbie95

I did the same thing as you but because I had my K as -4, I got completely different values. But that is a completely valid method I believe.

Same, I got K as -4! Don't know where I went wrong, but used all correct methods so out of the 12 marks for both the tangent and stationary point I hope to have got 8/9-ish :colondollar:

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Reply 132

username571327

Original post by mikemoore64

douse any one have the paper or is any one working on an unofficial mark scheme i would really like to know what i got ruffly.

*roughly

and mr m will put up unofficial MS tonight

Reply 133

motivatedshroom

I hope someone's cookin' up a mark scheme...

Reply 134

GeorgeBarrett1

How many marks can you drop and still get 100ums, or do you need full raw marks for 100ums?

Reply 135

Dugald

Original post by eggfriedrice

Guys, for the inequalities question
3-8x>4
Did you get x<-1/8 or x>-1/8

the first one

Reply 136

eggfriedrice

Original post by a10

1/4???? wer did u get that from I put

x>-3/2
x < 4

This is the quadratic right?

Question 8?

Original post by GeorgeBarrett1

How many marks can you drop and still get 100ums, or do you need full raw marks for 100ums?

if the A is 57 it may drop down to 71, and so on. its usually full raw in summer as everyone in yr 13 is resitting, or atleast thats the case in my 6th form