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# AQA C1 Unofficial Markscheme Watch

1. (Original post by smitherito)
Core 1 was much easier than previous papers
I agree it was a lot easier than the 2015 paper.
2. (Original post by rndmtngr99)
And I got root 55 for the circle question?!?
Yeah!!! I'm not alone!
3. Quick question, you know question 1. Did it give us the equation of AB or did we have to create it with the c=7. Or was the y=mx+7 there to confuse us??
4. I thought the equation for the tangent at P is y=-40x-56..... since Y-24=-40(x-2), how did you guys get gradient as -32...?
5. (Original post by BlackthornRose)
Here are my answers to the questions I can remember:

Surd question: 75-32 square root 5
Circle question: equation tangent I got 7x-4y+8=0
Equation circle (x-5)^2 + (y+3)^2 = 65 (I think I forgot to add on the additional numbers from completing the square and so got this wrong, please let me know)
Coordinates B I got (12, -7)
Length CT I got 9.
Integration question: equation of tangent I got y=-32x-40
x coordinate of Q I got -5/4
Area under curve
I think I correctly got the area under the curve which was 20.25 but after that I just messed up, how many marks do you think I lost for the question? I didn't recognise the whole area of triangle and minus that from the area under the curve.
Completing the square I got (x-7/2)^2 - 41/4
There was a transformation question too and I got a translation of 0.5 and -41/4, but looking back I'm not sure if I got the signs right, I think the y value was supposed to be positive in the translation? I'm sure I got that wrong.
Something about values for k I got k=4 and k=20.
Then something else about values for k I think it was (or was it x?) And I got k>6 and k<-3/2.
Another one about finding roots of an equation and I got x= -1+/- square root of 5.
Remainder theorem I got 20.
The linear factors I got (x+3)(x-4)^2 (can't remember if the first factor was plus or minus actually, just used the one they gave)
That's all I can remember at the moment; if anyone else can shed some light on the ones I'm not sure about and tell me roughly how many marks they think I lost?

Also, what do you suppose the grade boundaries are this year?

No, that's the right circle equation. The area under the curve was 20.25, subtract 9 (area of triangle) to get 11.25. The translation seems right. (x+3)(x-4)^2 was right, but I expect the mark scheme will require (x+3)(x-4)(x-4) - as it wanted 3 linear factors.Marks lost is hard to say tbh.
6. (Original post by TheOtherSide.)
You're back!
...guest appearance
7. (Original post by musslih)
I thought the equation for the tangent at P is y=-40x-56..... since Y-24=-40(x-2), how did you guys get gradient as -32...?
It should be been -32 - I can't remember the dy/dx tho. Then y-24 = -32(x + 2) as it was x--2.
8. (Original post by timtjtim)
No, that's the right circle equation. The area under the curve was 20.25, subtract 9 (area of triangle) to get 11.25. The translation seems right. (x+3)(x-4)^2 was right, but I expect the mark scheme will require (x+3)(x-4)(x-4) - as it wanted 3 linear factors.Marks lost is hard to say tbh.
Thanks, I just edited my post as well as i just realised it was in fact correct. Yeah I i got the area totally wrong. I wrote down both? Like, i wrote (x+3)(x-4)(x-4) or (x+3)(x-4)^2 just to make sure.

What do you suppose the grade boundaries will be like?
9. (Original post by BlackthornRose)
Here are my answers to the questions I can remember:

Surd question: 75-32 square root 5
Circle question: equation tangent I got 7x-4y+8=0
Equation circle (x-5)^2 + (y+3)^2 = 65 (I think I forgot to add on the additional numbers from completing the square and so got this wrong, please let me know)
Coordinates B I got (12, -7)
Length CT I got 9.
Integration question: equation of tangent I got y=-32x-40
x coordinate of Q I got -5/4
Area under curve
I think I correctly got the area under the curve which was 20.25 but after that I just messed up, how many marks do you think I lost for the question? I didn't recognize the whole area of triangle and minus that from area under curve thing.
Completing the square I got (x-7/2)^2 - 41/4
There was a transformation question too and I got a translation of 0.5 and -41/4, but looking back I'm not sure if I got the signs right, I think the y value was supposed to be positive in the translation? I'm sure I got that wrong.
Something about values for k I got k=4 and k=20.
Then something else about values for k I think it was (or was it x?) And I got k>6 and k<-3/2.
Another one about finding roots of an equation and I got x= -1+/- square root of 5.
Remainder theorem I got 20.
The linear factors I got (x+3)(x-4)^2 (can't remember if the first factor was plus or minus actually, just used the one they gave)
That's all I can remember at the moment, if anyone else can shed some light on the ones I'm not sure about and tell me roughly how many marks they think I lost?

Also, what do you suppose the grade boundaries are this year?

Edit: I actually just realised that I'm pretty sure my equation for the circle is right, as the equation is (x-a)^2 + (y-b)^2=r^2 and i worked out the radius using coordinates for centre and point A then just plugged it into equation.

Also, there was another question that asked for the value of k at a specific point like (3+5k, 4-3k) to the best of my memory, and I got k=-30.

Anyone else?
what about the question where you had to sketch the -2x"2 graph or something and state the y-intercept, any1 know how many marks that was? 2 or 3?
10. How did people get root 65 for the radius of the circle when the centre co-ordinates were (5,-3). On expanding this came out as root 34 surely?
11. (Original post by AyyS)
Quick question, you know question 1. Did it give us the equation of AB or did we have to create it with the c=7. Or was the y=mx+7 there to confuse us??
They gave the equation without the gradient and I'm sure we just had to find the gradient using the 2 coordinates they gave us and the gradient formula (m=y2-y1/x2-x1). I can't remember it properly but i think i got something like 4/7? Really can't remember.
12. (Original post by BlackthornRose)
Here are my answers to the questions I can remember:

Surd question: 75-32 square root 5
Circle question: equation tangent I got 7x-4y+8=0
Equation circle (x-5)^2 + (y+3)^2 = 65 (I think I forgot to add on the additional numbers from completing the square and so got this wrong, please let me know)
Coordinates B I got (12, -7)
Length CT I got 9.
Integration question: equation of tangent I got y=-32x-40
x coordinate of Q I got -5/4
Area under curve
I think I correctly got the area under the curve which was 20.25 but after that I just messed up, how many marks do you think I lost for the question? I didn't recognize the whole area of triangle and minus that from area under curve thing.
Completing the square I got (x-7/2)^2 - 41/4
There was a transformation question too and I got a translation of 0.5 and -41/4, but looking back I'm not sure if I got the signs right, I think the y value was supposed to be positive in the translation? I'm sure I got that wrong.
Something about values for k I got k=4 and k=20.
Then something else about values for k I think it was (or was it x?) And I got k>6 and k<-3/2.
Another one about finding roots of an equation and I got x= -1+/- square root of 5.
Remainder theorem I got 20.
The linear factors I got (x+3)(x-4)^2 (can't remember if the first factor was plus or minus actually, just used the one they gave)
That's all I can remember at the moment, if anyone else can shed some light on the ones I'm not sure about and tell me roughly how many marks they think I lost?

Also, what do you suppose the grade boundaries are this year?

Edit: I actually just realised that I'm pretty sure my equation for the circle is right, as the equation is (x-a)^2 + (y-b)^2=r^2 and i worked out the radius using coordinates for centre and point A then just plugged it into equation.

Also, there was another question that asked for the value of k at a specific point like (3+5k, 4-3k) to the best of my memory, and I got k=-30.

Anyone else?
I agree with the K=-30 but still unsure how you came to root 65 for the radius?
13. Was the values for k ----> (-3/2<k<6 ) or (-3/2>k or k>6)

*Brackets show the 2 different answers*
14. (Original post by BearackObama)
How did people get root 65 for the radius of the circle when the centre coordinates were (5,-3). On expanding this came out as root 34 surely?
To find the circle given C, you don't complete the square. The centre was 5,-3. You can say those are (a,b).

Now plug a,b into (x-a)^2 + (y-b)^2 = r^2

We get (x-5)^2 + (y+3)^2 = r^2.

Now for r - we know that A lies on this circle and is at coordinates A(-2,1). That gives a triangle, with sides 4 and 7. 7^2 + 4^2 = 65, so r = √65. But we want r^2, and √65^2 = 65 so k = 65.

My image may help - see attached.
Attached Images

15. (Original post by BearackObama)
How did people get root 65 for the radius of the circle when the centre co-ordinates were (5,-3). On expanding this came out as root 34 surely?
A(-2,1) C(5,-3)
(x-5)^2 + (y+3)^2 = k
sub A into it
(-2-5)^2 + (1+3)^2 = k
(-7)^2 + (4)^2 = k
49 + 16 = k
k = 65
16. (Original post by BlackthornRose)
Here are my answers to the questions I can remember:

Surd question: 75-32 square root 5
Circle question: equation tangent I got 7x-4y+8=0
Equation circle (x-5)^2 + (y+3)^2 = 65 (I think I forgot to add on the additional numbers from completing the square and so got this wrong, please let me know)
Coordinates B I got (12, -7)
Length CT I got 9.
Integration question: equation of tangent I got y=-32x-40
x coordinate of Q I got -5/4
Area under curve
I think I correctly got the area under the curve which was 20.25 but after that I just messed up, how many marks do you think I lost for the question? I didn't recognize the whole area of triangle and minus that from area under curve thing.
Completing the square I got (x-7/2)^2 - 41/4
There was a transformation question too and I got a translation of 0.5 and -41/4, but looking back I'm not sure if I got the signs right, I think the y value was supposed to be positive in the translation? I'm sure I got that wrong.
Something about values for k I got k=4 and k=20.
Then something else about values for k I think it was (or was it x?) And I got k>6 and k<-3/2.
Another one about finding roots of an equation and I got x= -1+/- square root of 5.
Remainder theorem I got 20.
The linear factors I got (x+3)(x-4)^2 (can't remember if the first factor was plus or minus actually, just used the one they gave)
That's all I can remember at the moment, if anyone else can shed some light on the ones I'm not sure about and tell me roughly how many marks they think I lost?

Also, what do you suppose the grade boundaries are this year?

Edit: I actually just realised that I'm pretty sure my equation for the circle is right, as the equation is (x-a)^2 + (y-b)^2=r^2 and i worked out the radius using coordinates for centre and point A then just plugged it into equation.

Also, there was another question that asked for the value of k at a specific point like (3+5k, 4-3k) to the best of my memory, and I got k=-30.

Anyone else?
Then something else about values for k I think it was (or was it x?) And I got k>6 and k<-3/2.
17. (Original post by Agent R5)
what about the question where you had to sketch the -2x"2 graph or something and state the y-intercept, any1 know how many marks that was? 2 or 3?
it was 2 marks
18. (Original post by vyyzx)
Was the values for k ----> (-3/2<k<6 ) or (-3/2>k or k>6)

*Brackets show the 2 different answers*
The latter. See image.
Attached Images

19. to work out radius of circle u needed to find the "difference" in x and y directions and use Pythagoras to find the actual length of it
if you do M1 you would be very familiar with this.
think of it like this, how do you get from co ordinates (10,10) to (5,6)
well you go -5 in x direction and -4 in y direction
now think of x and y as being horizontal and vertical respectively.
what is the hypotenuse of that triangle u have? ( hypotenuse = radius of the circle)
20. (Original post by Agent R5)
Then something else about values for k I think it was (or was it x?) And I got k>6 and k<-3/2.
Q7 I think , I got the same

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