AQA maths core 1, 13th May 2015

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Was the original translation equation:

X^2 - 3x +2
Or
X^2 + 3x +2

(Before you completed the square originally)

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Reply 241

woodchimp

Believe it was 48π not 49

Reply 242

Laurakat1

It was the first one, -3x

Reply 243

B82

How many marks was finding out the values of k?
And also how many marks was the graph of the sin curve

Reply 244

Why me

For the cylinder question, I took Pie out and got an answer of -12
as there was 2 pie so I took it out

Reply 245

B82

How many marks was finding out the values of k?
And also how many marks was the graph of the sin curve

Reply 246

aoxa

Original post by B82

How many marks was finding out the values of k?
And also how many marks was the graph of the sin curve

Which question for fining out k? There was the inequality one and circle one.

No idea why you're on about a sin curve - trig graphs are C2.

Reply 247

aoxa

Original post by Why me

For the cylinder question, I took Pie out and got an answer of -12
as there was 2 pie so I took it out

Did you eat the pie?

Reply 248

B82

Original post by aoxa

Which question for fining out k? There was the inequality one and circle one.

No idea why you're on about a sin curve - trig graphs are C2.

The one about the circle
The sin graph where it cut the axis at 0 and 3 but one of them was repeated

Reply 249

Why me

24pie r- pie/2r^3
differentiate
24- 3r^2/2

Differentiating Pie gives 1

Reply 250

Heffalump .

http://www.thestudentroom.co.uk/showthread.php?t=3322885 can people vote on the difficulty of the C1 exam poll? interesting to know how everyone found it

Reply 251

aoxa

Original post by B82

The one about the circle
The sin graph where it cut the axis at 0 and 3 but one of them was repeated

I think the answer was k=-2, k=8. I think it was 3-4 marks? I can't really remember.

And it wasn't a sin graph, it was a cubic graph, and the sketch I want to say was 2 marks, but don't take my word for that.

Reply 252

Heffalump .

These are the answers I remember:
q1: -3/5 for gradient
AB: -5x+3y-1=0
(9,-4)

q2: 7+ root15

q3: circle: (x+1)^2 + (y-3)^2 =50
C(-1,3)
radius: root 50, which is 5 root 2
k=8 k=-2 or something like that, I think i've remembered that wrong, so correct that
minimum length: 7

q4: dy/dx: 4x^3 - 6x or something..
the line was something like y=-10x-4
intergration: 108/5
final answer: (54-108/5) 162/5

q5: polynomials sketch curve
remainder: 36
proof p(x)=0
(x+2)((x^2-5x+10)
x^2-5x+10 has no roots (b^2-4ac < 0) so x=-2 is the only root

q6: cylinder
h=(48pi - pir^2)/2pir
prove v= that equation thing by substituting h in
dy/dx= 24pi-3pir^2/2
r=4
d^2y/dx^2=6pir
so -12pi therefore maximum

q7: (x+(3/2))^2 - 1/4
Vertex: (-3/2, -1/4)
Los: x=-3/2
translated curve: x^2-x+4

q8: rearrange to get that equation
use b^2-4ac<0 to get the second equation
-4/9<k<4
thats most of it, my memory failed at some parts so correct me if I'm wrong..

Reply 253

emilyt7

How many marks was the second part of the integration question??

Reply 254

B82

Original post by aoxa

I think the answer was k=-2, k=8. I think it was 3-4 marks? I can't really remember.And it wasn't a sin graph, it was a cubic graph, and the sketch I want to say was 2 marks, but don't take my word for that.

yeah sorry I meant a cubic graph!
but thanks!

Reply 255

Tiwa

Could you guys put the number of marks next to each answer please? Would greatly appreciate this!

Reply 256

student0042

Original post by Sharkindustries

Are you sure you are right??? Most of your answers match mine apart from 1c,3bi and bii

I'm not certain that i'm right, just the answers I got.

Reply 257

Laurakat1

I'm in a2 so this is a retake for me! I revised everything apart from stuff about cylinders because I completely forgot about them!! D: so annoying lol. Apart from that I thought it was great! :smile:

Reply 258

KingThomas

I messed up on the cylinder questions?

6

ENTIre question

how can you find a max or min if you got nothing to substitute in to dy2

Reply 259

Madmatician

These are most of the answers I think (the question references may be wrong):

1. (a) gradient = -3/5
(b) 5x - 3y = -1
(c) A(9, -4)

2. 7 + √15

3. (a) y - 6 = -10(x + 1)
(b) 21.6
(c) 32.4

4. (a)(i) (x+1)^2 + (y-3)^2= 50
(a)(ii) C (-1,3)
(a)(iii) Radius = 5√2
(b) k = -2, k = 8
(c) Shortest distance = 7

5. (a)(i) (x+1.5)^2 - 0.25
(a)(ii) vertex (-1.5, -0.25)
(a)(iii) line of symmetry: x = -1.5
(b) translated curve = x^2-x+4

6. (a) h = 24/r - r/2
(b)(i) V = hπr^2 = πr^2(24/r - r/2) = 24πr - πr^3/2
(b)(ii) r = 4, d^2V/dr^2 = -12π which is less than 0 therefore it's a maximum point

7. (a) polynomial sketch, repeated root at the origin, another root at x = 3
(b)(i) remainder = 36
(b)(ii) p(-2)=0 therefore x+2 is a factor
(b)(iii) (x+2)(x^2-5x+10)
(b)(iv) discriminant (b^2-4ac) of x^2-5x+10 is less than 0 therefore x=-2 is the only real root

8. (a) show x^2 + 3(k-2)x + 13 - k = 0
(b) the line and the curve don't intersect therefore the discriminant is less than 0, so use that to show 9k^2-32k-16<0
(c) 9k^2-32k-16<0 = (9k+4)(k-4)<0
therefore -4/9<k<4