You are Here: Home >< Maths

OCR MEI - FP1 - 14th May 2015 watch

1. (Original post by StrangeBanana)
That 1 should be negative. Fixed it now.

You were given the polynomial

And some information: the sum of the roots is 6, the product of the roots is -10, and one of the roots is 4. You had to find p, q and r.
How did you go about doing it??? I know I did it in the most convoluted way going.
2. (Original post by Aph)
How did you go about doing it??? I know I did it in the most convoluted way going.
You could get p and r immediately from the sum and product of the roots, and then I factorised the cubic (because (x - 4) was a factor) and deduced q from that.
3. (Original post by StrangeBanana)
You could get p and r immediately from the sum and product of the roots, and then I factorised the cubic (because (x - 4) was a factor) and deduced q from that.
I did the same as that except rather than factorising, i subbed in x=4 and made it equal to zero..

Also, 7ii is still incorrect as the second part of the inequality should be 0<=x<2 rather than 3<=x<2 !
4. (Original post by jpetersgill)
I did the same as that except rather than factorising, i subbed in x=4 and made it equal to zero..

Also, 7ii is still incorrect as the second part of the inequality should be 0<=x<2 rather than 3<=x<2 !
Sounds good.

5. (Original post by StrangeBanana)
You could get p and r immediately from the sum and product of the roots, and then I factorised the cubic (because (x - 4) was a factor) and deduced q from that.
I got those 2 yes but what I then did

and went from there... Do you think that's alright?
6. (Original post by Aph)
I got those 2 yes but what I then did

and went from there... Do you think that's alright?
Well I'm not sure about those upside down question marks.

So that gives you the third root, then what?
7. Anyone know how many marks each question was worth?

Posted from TSR Mobile
8. (Original post by StrangeBanana)
Well I'm not sure about those upside down question marks.

So that gives you the third root, then what?
Well it gives you the 2 roots then you add the 4 and multiply out. You have to put something in about beta and gamma being bi-variable and if one takes one value the other takes its complex congigate.
9. (Original post by Aph)
Well it gives you the 2 roots then you add the 4 and multiply out. You have to put something in about beta and gamma being bi-variable and if one takes one value the other takes its complex congigate.
Ah, fair enough. It's a valid method, so as long as you got the right answer I'm sure it'll be accepted!
10. (Original post by StrangeBanana)
Ah, fair enough. It's a valid method, so as long as you got the right answer I'm sure it'll be accepted!
Good, that was scary.the answer is 3 right?
11. (Original post by Aph)
Good, that was scary.the answer is 3 right?
Nope, p = -12, q = 11, r = 20. Bad luck.
12. (Original post by StrangeBanana)
Nope, p = -12, q = 11, r = 20. Bad luck.
Oh... Well I got the other 2 correct
13. (Original post by henrygriff28)
I did the exact same as you, do you think we'll still get the one mark? I think that would be all I dropped and I was hoping for 100 UMS so will be close.
Yeah can't lose 2 marks for getting it entirely right! Bullsh*t question, I didn't think I'd have to repeat the obvious lol
14. How many marks would one lose for not shading correctly in the Argand diagram? i.e didn't shade all the way down to minus one

Posted from TSR Mobile
15. (Original post by StrangeBanana)
Nope, p = -12, q = 11, r = 20. Bad luck.
NUUUUUUU I got r=123 T.T
16. (Original post by acelle)
NUUUUUUU I got r=123 T.T
There were 2 r's in the paper.
17. (Original post by Aph)
There were 2 r's in the paper.
O. Thanks that calmed my heart ..

Posted from TSR Mobile
18. (Original post by acelle)
NUUUUUUU I got r=123 T.T
:P yeah the other r was 123, don't worry
19. (Original post by StrangeBanana)
Unofficial Markscheme

1.

2.

3.

4.

5i. Use standard summations.

ii.

6. Run-of-the-mill proof by induction.

7i. Sketch:

ii. Values of x for which are:

8i.

ii.

iii. , or

iv. or

9i. A'(0, 0), B'(-4, 0), C'(2, 12)

ii. Horizontal enlargement with s.f. 4, vertical enlargement with s.f. 2

iii. The matrix required was:

iv. 192 sq. units

BUT will i lose some marks for the argand diagram question because for the part where you had do draw the argument boundries i used dotted lines instead of solid?
20. (Original post by Darcy1)

BUT will i lose some marks for the argand diagram question because for the part where you had do draw the argument boundries i used dotted lines instead of solid?
probs 1 or 2 marks because it shows that the line wasn't inclusive of that inequality, and it clearly was. So it sort of shows you didn't understand the condition fully.

Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: May 16, 2015
Today on TSR

A-Level OCR Biology Unofficial Markscheme

Find out how you've done here

1,761

students online now

Exam discussions