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C1 13/05/2015 Answer discussion

GabrielSmith1998

Finished the C1 exam a few hours ago. It was difficult in my opinion, and I will never get near to Jess' salary because of it. I am going to post some of the answers I got. You DO NOT have to assume that these are correct, they may be wrong so please do not panic if you answered differently. Feel free to post your own answers and share, I know it can be tempting to see if you are correct.
I cannot remember what every question was about but I think that I got the following answers:
Question1
a. 20
b. 3 + root 10
2. (I am not sure if this was question 2)
i. (x)(3+2x)(3-2x)
ii. 3root10 (k=3) <----very unsure about this
iii. Negative cubic, going though (-3/2,0) , (0,0) , and (3/2,0)
7.
a. y^2
b. x=-3,x=0
9.
a. Was a show that
b. £557,500
10.
a. can't remember the whole expression but I think that I got c=2.
b. x=3/2 <---tough one, really tough

for the question with recurrency formulas, I can't remember the question number but I think that I got the following answers:
a.
i. 4 ?
ii. 80 (20x4=80)
b.
i.3k,4k basically, Un=nk
ii.k=11 (165/15=11)
For the question with inequalities and p:
a. Show that question.
b. I am extremely unsure about this one, but I think that the answers might have been p>3+2root2, p<3-2root2.

(edited 8 years ago)

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Reply 1

Puddles the Monkey

Heya, I'm going to put this in the Maths forum for you as you should get more responses there.

You should also check out the forum to see if there's any other threads there which might be helpful to you!

http://www.thestudentroom.co.uk/forumdisplay.php?f=38

Reply 2

Yousf

Original post by GabrielSmith1998

Finished the C1 exam a few hours ago. It was difficult in my opinion, and I will never get near to Jess' salary because of it. I am going to post some of the answers I got. You DO NOT have to assume that these are correct, they may be wrong so please do not panic if you answered differently. Feel free to post your own answers and share, I know it can be tempting to see if you are correct.
I cannot remember what every question was about but I think that I got the following answers:
Question1
a. 20
b. 3 + root 10
2. (I am not sure if this was question 2)
i. (x)(3+2x)(3-2x)
ii. 3root10 (k=3) <----very unsure about this
iii. Negative cubic, going though (-3/2,0) , (0,0) , and (3/2,0)
7.
a. y^2
b. x=-3,x=0
9.
a. Was a show that
b. £557,500
10.
a. can't remember the whole expression but I think that I got c=2.
b. x=3/2 <---tough one, really tough

for the question with recurrency formulas, I can't remember the question number but I think that I got the following answers:
a.
i. 4 ?
ii. 80 (20x4=80)
b.
i.3k,4k basically, Un=nk
ii.k=11 (165/15=11)

For the question with inequalities and p:
a. Show that question.
b. I am extremely unsure about this one, but I think that the answers might have been p>3+2root2, p<3-2root2.

Pretty sure 1b was 3 plus root 5

Reply 3

anndz3007

i think question 9 a was not a show thing, i got the answer k=11 (the year)
Question 1 b was 3+root 5

(edited 8 years ago)

Reply 4

JhusJane

Awh wow you seemed have to done really well I got similar to you but made stupid mistakes now i come to think of your answers but i didnt don the last qs..ran out time but i managed to now awh so annoyed....

Just really praying grade boundaries are low...know ive missed like 11 marks for sure..

Reply 5

neo11

How did eveyone write 4^x in terms of y where y=2^x ?

Reply 6

JhusJane

Original post by neo11

How did eveyone write 4^x in terms of y where y=2^x ?

as y2 (y sqaured)

But made such a stupid mistake with the factoring completely lost my mind

Reply 7

PerplexedBird

Original post by neo11

How did eveyone write 4^x in terms of y where y=2^x ?

Well y= 2^x

to make 4^x

Then square both sides of y=2^x

so that it= y^2= (2^2)^x

That's what I did... not sure if steps are right but yeah it was y^2

(edited 8 years ago)

Reply 8

PerplexedBird

Original post by JhusJane

as y2 (y sqaured)

But made such a stupid mistake with the factoring completely lost my mind

For the factorising didn't you have to just substitute the 4 with y^2?

and y with the 2? so that it is a normal quadratic?

Reply 9

Dieselblue

Some one made the model answers
http://www.thestudentroom.co.uk/showthread.php?t=3322783

So far I marked my self and I predicted I am guaranteed at least a C, more likely a B.

Reply 10

zahraa.al-obaidi

I couldn't do the discriminant question. on part B I completed the square.

Reply 11

shahkr

Hi, do know for the graph question I drew my line from bottom instead of top but got the same coordinates, how many marks will I get out of 3? Also for the 7b the power question I left it to y=1/8 and y=1, I didn't solve it, how many marks will I get???

Reply 12

Nadeem12

you know for the 9x+4x^3 graph question, I wrote the co-ordiantes as 3+2x, 0 0,0 and 3-2x, 0 , Idek why i did that, in hindsight, but how many marks would i lose for that?

Reply 13

vis break

Original post by zahraa.al-obaidi

I couldn't do the discriminant question. on part B I completed the square.

I did that too, but then I didnt cancel down sqrt(8.....
F****!!!

Reply 14

thenextchemist

Original post by shahkr

1 mark for the coordinates
0 for the curve
I think it's one mark for the (0,0) point

Posted from TSR Mobile

Reply 15

MadZler

Pretty sure only mistake I did was to forget to divide the 4root2 part of the inequality by 2... Stipid... I got 3 + root10 for 1b as well. Everything else from OP seems right :smile:

Good luck on C2 next week guys, and good luck for those who are taking FP1 tomorrow, I will be doing it too :smile:

And yeah, I hate Jess' job too.

Reply 16

snowflake97

Pretty sure 1b gave something along the lines of 'write your answer in the form a + b√10'

Reply 17

MadZler

Original post by snowflake97

Pretty sure 1b gave something along the lines of 'write your answer in the form a + b√10'

Yup, and that was a=3 b=sqrt(10)

Reply 18

GabrielSmith1998

Original post by Yousf

Pretty sure 1b was 3 plus root 5

I

I think that you are mistaken.
I am guessing that you accidentally made 2root10 root5 by accidentally dividing both the 2 and 10 by 2. i think that it should have been root10 (with the +3)