AQA maths core 1, 13th May 2015

Original post by Rob194656

I think most people have said d2y dx2 was -12pi, which is the simplified version of what I wrote.

I used the value 3.14 instead of pi and got -37.68 and said it is a maximum will i get the marks.

Reply 841

Original post by marklowell96

I used the value 3.14 instead of pi and got -37.68 and said it is a maximum will i get the marks.

how did you do that calculation in your head in the first place? but yes you will still get the marks and was it definitely 12 pi because I got that answer but my teacher said it was 12r earlier?

Reply 842

Original post by r-star

What was d2y/dx^2 i got 24-3pir is thiss right?

Dy/Dx was 24-3piR^2 I think then d2y/dx2 was -3Pi I think?

Reply 843

marklowell96

Original post by JackMac123

how did you do that calculation in your head in the first place? but yes you will still get the marks and was it definitely 12 pi because I got that answer but my teacher said it was 12r earlier?

12*3=36
12*0.14=12*14/100 so I got 168/100=1.68

36+1.68=37.68

because it was negative 2 i placed a negative in front of my answer

Reply 844

Original post by r-star

so how was max=-12pi?

Because d2y/dx2 was -3pi because that was differentiated from 24-3piR

Reply 845

Original post by marklowell96

12*3=36
12*0.14=12*14/100 so I got 168/100=1.68

36+1.68=37.68

because it was negative 2 i placed a negative in front of my answer

Fair enough, I just left it as -12pi, I am just worried whether it was -12pi because I got that answer however someone in my class got a different answer

Reply 846

marklowell96

Original post by JackMac123

Fair enough, I just left it as -12pi, I am just worried whether it was -12pi because I got that answer however someone in my class got a different answer

Pretty sure it was the majority of people in my class got that. :smile:

Reply 847

r-star

Original post by JackMac123

Because d2y/dx2 was -3pi because that was differentiated from 24-3piR

Dy over dx was 24pi-3pir^2/2
D2y over dx2 i got as 24-3pir

Reply 848

crimson1234

Hey for the question numbers i wrote just -a- and for parts just -ii- not -a-ii- does it matter as long as its clear what question you are answering

Reply 849

bunulot

What was the equation of the curve in this question?

Reply 850

bunulot

What was the equation of the curve in the integration question?

Reply 851

-jordan-

5

Original post by JackMac123

Fair enough, I just left it as -12pi, I am just worried whether it was -12pi because I got that answer however someone in my class got a different answer

The second derivative came out to -12pi :smile:

Reply 852

SunDun111

11

Original post by ProNoob

Worst case senerio 0
Best case senerio 2

Posted from TSR Mobile

Surely I can't get 0 I still got stationary value as 4

Reply 853

r-star

Original post by SunDun111

Surely I can't get 0 I still got stationary value as 4

1 mark for stating dy/dx=0
1 mark for r=4
1 mark for getting g d2y/dx^2 i think was 24-3pir??
1 mark for saying -12pi-maximum
????
or maybe you wont get mark for dy dx =0 butfor subbing in r=4 in d2y/dx^2

Reply 854

J-To-The-Era-Wig

What did you guys get for the remainder question, where the equation had to be divided by x-4?

Reply 855

C0balt

16

Original post by J-To-The-Era-Wig

What did you guys get for the remainder question, where the equation had to be divided by x-4?

36 if I remember correctly

Reply 856

SunDun111

11

Original post by r-star

1 mark for stating dy/dx=0
1 mark for r=4
1 mark for getting g d2y/dx^2 i think was 24-3pir??
1 mark for saying -12pi-maximum
????
or maybe you wont get mark for dy dx =0 butfor subbing in r=4 in d2y/dx^2

I made dy/dx = 0 and got 4 but d2y/dx2 I did wrong, would I get two

Reply 857

J-To-The-Era-Wig

Original post by C0balt

36 if I remember correctly

Ahhh good, I got that but I didn't do long division :/ will I lose a mark or two for that?

Reply 858

username1136031

Original post by J-To-The-Era-Wig

Ahhh good, I got that but I didn't do long division :/ will I lose a mark or two for that?

No, it asked you to use remainder theorem i.e. plugging a value into the equation and seeing what comes out. The only time you need to use algebraic division is when it asks you for the quotient and the remainder.

Reply 859

J-To-The-Era-Wig