OCR (not MEI) C1 - Wednesday 13th May 2015

if an A was say 62, what mark will be required for 100 UMS? 71 or 72?

what was the question involving k?

Anyone else get 20 root 5 for the last one?

40 seems to be what most people agree on.

can anyone remember the find a question

just wanted to check something

so like for the last question, i just wrote "the area is 40" - do you need to specify 40 square units? Similarly I said the radius of circle was 5, not 5 units.

wait so the question about the stretch in the x-axis was not scale factor 3? how can it be 1/3 ?

I think I got a=13 for that one..?

A few definite correct answers:
1) first question was 4(√ 3)+4
2) indices:
i) 5^8
ii) 5^(-1/4)
iii) 5^(9/2)
3) with two simultaneous equations, solutions were:
x=14/3, y=-13/3, and
x=2, y=1
4) The quadratic with unknown 'a', a=13
5) transformations:
i) 1/(x-2)^.... (Can't remember the denominator power - it was the '-2' that's important)
ii) the one with denominator '3x' was a stretch scale factor 1/3 parallel to the x-axis (in the x direction) OR parallel to the y axis (in the y axis) as both do the same transformation in this example.
X DIRECTION AND Y DIRECTION BOTH RIGHT!
6) with another quadratic curve question, with something like 2x^2-x-3=0;
The curve intercepted the x axis at -1 and 3/2, and the y axis at -3.
When it asked for the values of k, k<-25/8
7) with the curve y=x^(-1/3) and at the point x=-8, the gradient was -1/48
8) the circle question: centre (5,-2), radius 5.
The then triangle PQR later in that question had area 40.
Sorry if they aren't in their test order, and good luck everyone doing C2 tomorrow!

Y=-1/x => y=-1/3x.
This could be done by either multiplying the x by 3, which is equivalent to y=f(ax) so would be scale factor 1/3 in x direction. Alternatively you could multiply the whole original function by 1/3 which is equivalent to y=af(x) so would be scale factor 1/3 in y direction.

Can't remember the question order so sorry if it's wrong (it's definitely wrong). From what I can remember:
1) 4 + 4root3
2) can't really describe the graph, if you know what y=1/x looks like then reflect in either axis.
Translation of 2 in x was -1/(x-2)
The translation they wanted you to state was a stretch of 1/3 in either axis.
3) 5^8
5^(-1/4)
5^(9/2)
4) was this the one with k?
Factorise the quadratic, draw graph. For y>0, x<-1 or x>3/2
K < -25/8
5) differentiation? Can't remember the answer to this, was reasonably straight forward though if you expanded brackets.
6) simultaneous equation - x=1, y=2 or x=14/3, y=-13/3? Not sure about signs
7) differentiate x^(-1/3)? Should get out -1/48 when you put x in.
8) coordinate geometry? Line was something like 6x-8y-29=0
9) a=13
Second derivative was positive therefore min points
X=1/3
10) centre (5,-2) radius 5
Prove tangent
Area of triangle = 40
I've just realised how much I really cannot remember the order. These are my answers which seem to be generally accepted within my school and by various people on here. They may not be right.

For question 6 it was y=5-2x so your first x and y solutions arent valid.

I got X=2 y =1
And x=14/3 y=-13/3

So what would this be?
(iii) The curve y =x^1/2 is stretched by a scale factor of 5 parallel to the x-axis. State the equation of thetransformed curve.

find a given that x=4 was a stationary point or something

like can anyone remember f(x)

Y=(x/5)^1/2

Couldn't remember which way the x and y were. 2 and 1 were definitely right, though I probably got them mixed up when I was trying to remember what I wrote to post this. I'll change it now, thanks.