OCR Core Maths

Same! I definitely got that!

You're all right, the answer that was posted on page 1 is wrong. The person mixed up x and y.

PS: Ignore my -1 reputation. I have NO IDEA how that happened...

Helping you out with a +1 haha

I can confirm it was 8x + y + 13 = 0

Reply 61

rbh

Coordinates of the transformed graphs, I got:
y = f(x) + 2 as (2,7)
y = f(2x) as (1,5)

Anyone get that?

Reply 62

MattEvans

What did everyone get for the question were you had to find the equation of line which goes through A and is perpendicular to AB, I got x +2y -19=0

Reply 63

manchestermadnes

I thought it was just k=-2 and k=-8 as it was finding a pair of coordinates?

Posted from TSR Mobile

Reply 64

xx_Dan_xx

Original post by Peanut247

How did people confirm that the circle did not pass the x axis and also where you had to find the y coordinate of the intercept from the tangent lind?

The centre y coord + radius will give the coords of the highest point of circle which was 0. this proves it touched it but didnt cross.

Reply 65

Wiggledinho

3

Original post by rbh

Coordinates of the transformed graphs, I got:
y = f(x) + 2 as (2,7)
y = f(2x) as (1,5)

Anyone get that?

yeah

Reply 66

xx_Dan_xx

Original post by manchestermadnes

I thought it was just k=-2 and k=-8 as it was finding a pair of coordinates?

Posted from TSR Mobile

It asked for a range of values which means inequality.

Reply 67

PeaceTreaty

OP

8

I'm not sure if I did my cubic sketch correctly, it was a positive cubic right? So it was in quadrants 1, 3 and 4 due to it being effect by other terms and the gradient was +ve initially and negative at the end, I found x=-2 to be a maximum point as it's tangent to that point and is +be initially and intercepts y at -12 (I think) and it then it went through x=2/3

Reply 68

manchestermadnes

Original post by xx_Dan_xx

It asked for a range of values which means inequality.

It didn't ask for a range, it said a set of values. If the circle already has seet coordinates then you know exactly what k is

Posted from TSR Mobile

Reply 69

xx_Dan_xx

Original post by PeaceTreaty

I'm not sure if I did my cubic sketch correctly, it was a positive cubic right? So it was in quadrants 1, 3 and 4 due to it being effect by other terms and the gradient was +ve initially and negative at the end, I found x=-2 to be a maximum point as it's tangent to that point and is +be initially and intercepts y at -12 (I think) and it then it went through x=2/3

Yes it was a + cubic. You didnt need to find the maximum point. The question gave you the three roots whilst expanding gave you the y intercept. Type the equation into google to get the grapg to check whether it is right.

As for myself, I think all got full marks - any marks lost for not putting +- in some root equations so overall loss of 3 at most.

Reply 70

TheRAG

2

Original post by Jamsong

Does anybody remember the last question so that I can redo it now and check what answer I got ?

Find the equation of the tangent to the curve (2x-3)(x+2)²

Reply 71

Minecraft27

14

Original post by manchestermadnes

It didn't ask for a range, it said a set of values. If the circle already has seet coordinates then you know exactly what k is

Posted from TSR Mobile

By "set of values" it means the range of values.
It wasn't asking for individual co-ordinates. It had to be an inequality written as -8<k<-2.

Reply 72

e_burns

For finding the values of k, it was an inequality because it asked for where k was inside the circle, rather than on it.

Reply 73

C1mathsquestion

For the last one I thought because it was a tangent the gradient would become 1/8 rather than -8 but obviously that's wrong having looked at other peoples answers. Anyone know how many follow through marks I'd be likely to get if I've done the rest right?

Reply 74

xx_Dan_xx

Original post by manchestermadnes

It didn't ask for a range, it said a set of values. If the circle already has seet coordinates then you know exactly what k is

Posted from TSR Mobile

You had to use the Point P and the Centre in Pythag when it was less than the radius^2. This introduces the inequalities giving you a ranges. K can be any coord between whatever the answers were. Because between those values the length was still inside the circle.

You were never given a length but only know it lies inside the circle which means the you had to add the inequality which was less than the radius squared.

Reply 75

PeaceTreaty

OP

8

Original post by xx_Dan_xx

Yes it was a + cubic. You didnt need to find the maximum point. The question gave you the three roots whilst expanding gave you the y intercept. Type the equation into google to get the grapg to check whether it is right.

As for myself, I think all got full marks - any marks lost for not putting +- in some root equations so overall loss of 3 at most.

I thought it was two roots, doesn't (x+n)^2 mean that there's a repeated root at x=-n?

Reply 76

username1107011

1

Original post by manchestermadnes

It didn't ask for a range, it said a set of values. If the circle already has seet coordinates then you know exactly what k is

Posted from TSR Mobile

(6,k) was 'inside' the circle, meaning it k could be anything between -2 and -8.

Reply 77

germankid101

6

For showing how the circle does not lie above the x axis, I showed that because the radius is 5, it only touches the x axis and cannot go above with 2 calculations demonstrating this. Is that what you guys did too?

Reply 78

Minecraft27

14

Anyone else get +-1/2 for the hidden quadratic?

5(x+1)^2 -3 for completing the square?

x+2y-19=0 for the perpendicular line (I don't remember exactly what I got. The plusses or minuses might be the other way round).

Reply 79

Wiggledinho

3

Original post by germankid101

For showing how the circle does not lie above the x axis, I showed that because the radius is 5, it only touches the x axis and cannot go above with 2 calculations demonstrating this. Is that what you guys did too?

yeah thats what I did

OCR Core Maths

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