AQA A Level Maths Core 2 - 25th May 2016 [Exam Discussion]

Yep, I got the same as you did.
But they said the transformation was 3√x^2 + 1 not 3√x^2 + 9 which totally confused me.

I remember when I looked at the question it was 3√x^2 + 9, right??

I just really didn't know whether I read the question wrong or not.

I believe the answer was stretch in x s.f. 1/3, just checked on a graph. I believe it was from y = √x^2+9 to y = 3√x^2+1, which is a stretch in x s.f. 1/3.

Reply 241

1039ab789o

7

Original post by goofyygoober

then stretch in x-direction by sf 1/3 is correct :frown:

I think it's 3:
3(x^2 +1)^1/2 =
= ( 9(x^2+1) )^1/2 = (9x^2 + 9)^1/2 =
( (3x)^2 + 9 ) ^1/2
So it has basically changed from (x)^2 in the original to (3x)^2
That means it's been timesd by 1/3 Inside the bracet, and so it has a sf of 3 (because with x the transformations are opposite )

Reply 242

Excuse Me!

19

Original post by goofyygoober

Yep, I got the same as you did.
But they said the transformation was 3√x^2 + 1 not 3√x^2 + 9 which totally confused me.

I remember when I looked at the question it was 3√x^2 + 9, right??

I just really didn't know whether I read the question wrong or not.

tbh i totally didn't see that what was in the square root changed.

it was definitely 2 marks which is always one named transformation and then the scale factor / vector to get 2 marks so since there was definetly a stretch we'll get the marks.

Maybe it was to confuse people?

Reply 243

Thash12

1

1)b) was definitely -2
9)a) ^m/2 - 6n

Reply 244

goofyygoober

8

Original post by salome12

I think it's 3:
3(x^2 +1)^1/2 =
= ( 9(x^2+1) )^1/2 = (9x^2 + 9)^1/2 =
( (3x)^2 + 9 ) ^1/2
So it has basically changed from (x)^2 in the original to (3x)^2
That means it's been timesd by 1/3 Inside the bracet, and so it has a sf of 3 (because with x the transformations are opposite )

if you type the equation on your graphic calculator, you will see that f(x) has become narrower in x-direction which means it is 1/3

Reply 245

Astro_Joe

1

Stretch s.f. 1/3 in the x direction was correct. If you do a stretch scale factor a, you replace the variable (in this case x) with x/a, giving you x/(1/3) which left you with 3x. Then it was (3x)^2 to give you 9x^2, so you could take 9 out as a factor (of 9x^2 + 9) and then square root it to get y = 3sqrt.(x^2 + 1.)

Reply 246

goofyygoober

8

Original post by Excuse Me!

tbh i totally didn't see that what was in the square root changed.

it was definitely 2 marks which is always one named transformation and then the scale factor / vector to get 2 marks so since there was definetly a stretch we'll get the marks.

Maybe it was to confuse people?

I hope so. Really ran out of time to check the questions.

Reply 247

money-for-all

17

i left the normal equation in the form y-y1 = m(x-x1)

how many marks willl i lose

Reply 248

BenAtkinson

2

Original post by money-for-all

i left the normal equation in the form y-y1 = m(x-x1)

how many marks willl i lose

Im guessing you subbed numbers in to y1 and x1? If so, none. They normally accept all forms, unless they state otherwise. I, myself, simplified it to y + 2x = 13 which made it easier in the next question but you should be okay.

Reply 249

money-for-all

17

Original post by BenAtkinson

Im guessing you subbed numbers in to y1 and x1? If so, none. They normally accept all forms, unless they state otherwise. I, myself, simplified it to y + 2x = 13 which made it easier in the next question but you should be okay.

Woooooo i love you buddy!!!!
remind me how many marks this was again
thanks

Reply 250

igotnomoney

13

Original post by TIF141

Somehow I got 4096 for the binomial expansion, think I must have forgot to put in the minuses or something!! D:

I got the same, i think i forgot minuses too :frown:

well i got Methoda mark ehh

Reply 251

Zohrayasin

1

For the perimeter I got 15 .1 I used the area 19.9 then divided by 2 and than times by 2 and than used the angle and divided it and I get radius 34 I think and than I square rooted ani got 5 .82 and than I times it by two and foung the arc lengh and than I got 15.1

Reply 252

alkaline.

17

Original post by Bradley99

IMO that's very harsh. But at the end of the day I think I may have got 67 so probably 90 UMS, which I'm happy with :smile:

how much UMS would around 60/63 / 75 be?

also how many universities look at individual UMS for modules?

Original post by Zohrayasin

For the perimeter I got 15 .1 I used the area 19.9 then divided by 2 and than times by 2 and than used the angle and divided it and I get radius 34 I think and than I square rooted ani got 5 .82 and than I times it by two and foung the arc lengh and than I got 15.1

do you remember how many marks this question was worth in total?

Reply 253

money-for-all

17

for sketch y=2^x

i put (1,0) by mistake

but the sketch was correct,
and above the sketch i said 'when x=0 , y=1'

but i put the corordinate the other way around

will i still get the full marks ?

Reply 254

Jackmilne95

2

How did you find u12 for the arithmetic series. I got a = -12 and d= 2 but that's wrong. I couldn't work out how to do it.

Reply 255

Slime101

14

Original post by Jackmilne95

How did you find u12 for the arithmetic series. I got a = -12 and d= 2 but that's wrong. I couldn't work out how to do it.

i got a and d but didnt have time to find u12 what is did was use the equation in the question before and use n/2 = (2a+(n-1)d) to find an equation for u12 and do simultaneous equations to find a= 28 d= -2

Reply 256

SunDun111

11

i got about 53? anyone any idea what grade this is.

Reply 257

MotorboatMyGoat

2

Original post by alkaline.

how much UMS would around 60/63 / 75 be?

also how many universities look at individual UMS for modules?

do you remember how many marks this question was worth in total?

Should just get you an A
Only really Oxford and Cambridge
6 marks for perimeter I believe

Reply 258

alkaline.

17

Original post by MotorboatMyGoat

Should just get you an A
Only really Oxford and Cambridge
6 marks for perimeter I believe

honestly I think I GOT LIKE 55/75.....
**** my entire life.

i think I got near perfect on c1 (As expected) but *if* I get near perfect on stats do you still think overall I can get an A?

Reply 259

username1767537

9

Original post by Zohrayasin

For the perimeter I got 15 .1 I used the area 19.9 then divided by 2 and than times by 2 and than used the angle and divided it and I get radius 34 I think and than I square rooted ani got 5 .82 and than I times it by two and foung the arc lengh and than I got 15.1

Perimeter was 13.8 to 3.s.f

Note premature rounding may have skewed accuracy

r=√(19.9/0.586) = 5.82743892

Side 1→ 9 – 5.82743892 = 3.17256108
Side 2 → 8 – 5.82743892 = 2.17256108
Arc Length = rθ = 3.414879207
Unaffected length of 5

Perimeter = [Side 1] + [Side 2] + [Arc Length] + [Unaffected Length]

Perimeter = 13.76000137

To 3 s.f = 13.8

AQA A Level Maths Core 2 - 25th May 2016 [Exam Discussion]

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