The Student Room Group

OCR MEI AS Mathematics Core 1 13/05/2013

Scroll to see replies

Reply 200
Original post by PreppyNinja
Hope so. Was the Y-value 2root11?


2-rt11 and 2+rt11 because the roots can be positive and negative, and the circle crosses twice
Reply 201
Original post by Deceived
I think the equation went:

V=1/3*pi*r2*(a+b)
3V=pi*r2*(a+b)
3V/pi=r2*(a+b)
3V/(pi*(a+b))=r2
r=Pos/Neg (3V/(pi*(a+b))1/2


Hope that helps.


Think the root had to be positive as it said r>0
You know if the grade boundaries aren't low, I think I managed a C/B which is bad! :/
Reading your answers made me depressed and now I gotta work harder on the other too.

Too many silly mistakes
Reply 203
Original post by jojo19apr
Think the root had to be positive as it said r>0


Yeah I forgot the question. That was just off the top of my head. Hopefully, in the exam I didn't put (pos/neg). Can't remember.
Reply 204
Original post by Soho32
for the evaluate 0.2^-2 was it okay to leave the answer as a fraction? i.e 1/0.04?


Not sure as it said simplify, and you haven't fully simplified it. I found it easier to look at it as (1/5)^-2, then you have 5^2 and can see easier that it is actually 25.
Original post by jojo19apr
Not sure as it said simplify, and you haven't fully simplified it. I found it easier to look at it as (1/5)^-2, then you have 5^2 and can see easier that it is actually 25.


omg cant believe i didnt see that :frown:

Posted from TSR Mobile
Original post by TheNote
the answer was 25;

(1/5)^-2

(5/1)^2

5^2 = 25


since 1/0.04 = 25 then you should be okay :smile: even if youe method is a bit of a weird way round it.


Do you think a triple decker fraction is ok - I put 1/(1/25) ?


Posted from TSR Mobile
Reply 207
Original post by krishkmistry
Do you think a triple decker fraction is ok - I put 1/(1/25) ?


Posted from TSR Mobile


yeah because they are equivilent:
1/1/25 = (1*25)/1
Guys what about the question 4 or 5
It was something like 10+7sqrt5 + 38 over 1-2sqrt5
Does anyone know of an unofficial mark scheme available online?
Reply 210
Original post by Sonicsuper
Guys what about the question 4 or 5
It was something like 10+7sqrt5 + 38 over 1-2sqrt5


Yeah:

10+7√5+38/(1-2√5)

=10+7√5+(38)(1+2√5)/(1-2√5)(1+2√5)

=10+7√5+(38+76√5)/(1-2√5+2√5-4√25)

=10+7√5+(38+76√5)/(-19)

=10+7√5-2-4√5

=8+3√5

That's what I got. Hope this helps.
Original post by Deceived
Yeah:

10+7√5+38/(1-2√5)

=10+7√5+(38)(1+2√5)/(1-2√5)(1+2√5)

=10+7√5+(38+76√5)/(1-2√5+2√5-4√25)

=10+7√5+(38+76√5)/(-19)

=10+7√5-2-4√5

=8+3√5

That's what I got. Hope this helps.

I got 12 + 11root5....
Reply 212
Original post by Sonicsuper
I got 12 + 11root5....


Please post your working out.
Original post by Deceived
Please post your working out.

Sorry i found my mistake, your answer was right!
Reply 214
Original post by Sonicsuper
Sorry i found my mistake, your answer was right!


No problem. I made an egregious error in the exam. I'm so fortunate I checked my answers.
Reply 215
Reckon 56 for an A
Reply 216
Is there an unofficial mark scheme available anywhere by any chance?
Reply 217
Original post by Sonicsuper
I got 12 + 11root5....


All you did wrong was add (2 + 4root5) instead of taking away. Otherwise you would have got the right answer
Do you reckon I would have lost a mark for putting pos/neg in that rearranging question when r>0?
(edited 10 years ago)
I think you would because it said r>0

Quick Reply

Latest