Maths HL P 1 - aftermath

**Timbuk2**

Deleted User wrote: »

I went with 'otherwise' and proved it by induction.

That's sheer genius

karen-xxxxx

Did anyone get
b = 4
c = -7
and d = - 10
for Question 1, part c?

kieran--f

karen-xxxxx wrote: »

Did anyone get
b = 4
c = -7
and d = - 10
for Question 1, part c?

no got -11/4 -7/2 and 1/4 haha surely wrong

karen-xxxxx

kieran--f wrote: »

no got -11/4 -7/2 and 1/4 haha surely wrong

awh man, i'm probably wrong. Ohwell a lovely paper otherwise

**Timbuk2**

karen-xxxxx wrote: »

Did anyone get
b = 4
c = -7
and d = - 10
for Question 1, part c?

I got those answers!

Indigo Sunrise

Did anyone else forget to put in the make of their calculator?
what happens if you don't?

karen-xxxxx

**Timbuk2** wrote: »

I got those answers!

Oh great, I filled in x for two and x for minus one after words and they worked out as factors so i hoped it was right.

Trackmedown

did anyone else get like really weird looking decimals in the complex number question (part c)?

thought the paper was alritish accept 4 that curve thingy... took a wild guess and said asymatope (i no i cant even spell it!) lol

karen-xxxxx

Trackmedown wrote: »

did anyone else get like really weird looking decimals in the complex number question (part c)?

thought the paper was alritish accept 4 that curve thingy... took a wild guess and said asymatope (i no i cant even spell it!) lol

Ya they were decimals, but when you used one for w, if the i's cancelled ( showing it was real) then they were probably right

CantStandMeNow

Trackmedown wrote: »

did anyone else get like really weird looking decimals in the complex number question (part c)?

thought the paper was alritish accept 4 that curve thingy... took a wild guess and said asymatope (i no i cant even spell it!) lol

Yup we were supposed to leave it in polar form.. I did the same thing.. we just went one step too far.. i dunno if they can take marks off for that because technically we just went too far but its still right?

eoins23456

got those answers as well but then realised they werent in arithmetic order.but then got the answer that were posted by ur man

citizenerased1

mark.oc wrote: »

Q.1 (a) k = -3, t = 9

(c)(i) -3-b
(ii) -2-2b
(iii) b = -4, c = 1, d = 6

Q.2 (a) x = 3, y = -2, z = -1

(b)(i) 4
(ii) rt20 or 2rt5

Q.3 (a) x = 4, y = 2

(b)(i) ±6
(ii) -8

(c) Didn't take them down as they were all decimals.

Q.4 (a) 47/99

(b)(i) a = -42, d = 6
(ii) 0

(c)(iii) 27230

Q.5 (a) x = 2

(c)(ii) 47

Q.6 (a) x = 4/3

(b)(i) 2/5
(ii) line

(c)(i) [LATEX](-4-2xy^3)/(2+3x^2y^2)[/LATEX]
(ii) 2x + y - 6 is the tangent.

Q.7 (b)(i) 2/(1-2cosxsinx)

(c)(ii) minimum

Q.8 (a) -(cos2x)/2 + (e^4x)/4 + c

(b) 37 units

(c)(i) ln((1+sinb)/(1+sina))
(ii) ln((1+cosa)/(1+cosb))

Q.7 (b)(i) 2/(1-2cosxsinx) ya suree? i got 2/(cosx - sinx)^2 it works out in the next part perfectly too...
got 27 units for area
and the square root of 16P^2 + 1 for 1(B)

1 and 2 were grand
and im a highly average student normally :P
SCOREEEEE

CantStandMeNow

citizenerased1 wrote: »

Q.7 (b)(i) 2/(1-2cosxsinx) ya suree? i got 2/(cosx - sinx)^2 it works out in the next part perfectly too...
got 27 units for area
and the square root of 16P^2 + 1 for 1(B)

1 and 2 were grand
and im a highly average student normally :P
SCOREEEEE

I got 2/(1-2cosxsinx) aswell.. it worked out perfectly in the next part too

The proof of the p thing in Q1 was 16p^2 > -1 right? Makes sense anyway.

eoins23456

citizenerased1 wrote: »

Q.7 (b)(i) 2/(1-2cosxsinx) ya suree? i got 2/(cosx - sinx)^2 it works out in the next part perfectly too...
got 27 units for area
and the square root of 16P^2 + 1 for 1(B)

1 and 2 were grand
and im a highly average student normally :P
SCOREEEEE

the 1-2cosxsinx in the same thing as (cosx -sinx) squared:)

NumberZeroNine

citizenerased1 wrote: »

Q.7 (b)(i) 2/(1-2cosxsinx) ya suree? i got 2/(cosx - sinx)^2 it works out in the next part perfectly too...
got 27 units for area
and the square root of 16P^2 + 1 for 1(B)

1 and 2 were grand
and im a highly average student normally :P
SCOREEEEE

I got 27 too, posted a reply on page 10 or 11 asking how it would be marked, did you make the same mistake (I have the details in that post)?

Ruski

That paper was absolutely tasty. I did all 8 questions with another half an hour to spare. The only thing that caught me out was question 2 (b) and maybe the past c of question 7 but that's just about it. Question 4 part C threw me off as well. I couldn't remember anything for that stuff.

karen-xxxxx

NumberZeroNine wrote: »

I got 27 too, posted a reply on page 10 or 11 asking how it would be marked, did you make the same mistake (I have the details in that post)?

The area is 37, because the -32 changes to positive because it is on the opposite side of the x axis to the five.

CantStandMeNow

karen-xxxxx wrote: »

The area is 37, because the -32 changes to positive because it is on the opposite side of the x axis to the five.

It was 37, our teacher did it out after!

Edit: Oh sorry just saw it wrong haha

DancingQueen:)

I got 153 for the area At first I did it by differentiation and realised about 5 minutes before the end and changed it all. I was obviously wrong but pretty sure I got the method right (the second time) so hopefully I won't lose too many marks.

Reillyman

For 8.(C)(iii) did everyone use the [latex]
sin(pi-a)=cosa[/latex] and [latex]cos(pi-b)=sinb[/latex] ?

EuropeanSon

Reillyman wrote: »

For 8.(C)(iii) did everyone use the [latex]
sin(pi-a)=cosa[/latex] and [latex]cos(pi-b)=sinb[/latex] ?

Surely you mean sin(pi/2 -b)=cos(b)?

NumberZeroNine

Reillyman wrote: »

For 8.(C)(iii) did everyone use the [latex]
sin(pi-a)=cosa[/latex] and [latex]cos(pi-b)=sinb[/latex] ?

I let b = pi/2 - a

And then solved it using the compound angle formulae. Sin90 and Cos90 nicely chopping it down when multiplied.
I'm not saying that your way wouldn't work but I was working on proofs on wednesday and they just came to mind straight away.

Angles of (90 [which is pi/2] - A) change the function ie sin(90-A)= cosA

DGRulz

Im very unsure about this paper. I thought it was hard when I walked out but looking at it now it seems easier. got 127 for the area but forgot to right units and got 8 for 3bii and just realised i did out 6 roots for ci :S. I knew how to do 2bii but couldnt remember the order of things. TBH i was so drained that by the time I got to 1 and 2. Despite the fact i knew how to do it I couldnt do 1c . For 2ci i brought the ab across and reduced it to (a-b)squared and the left a note saying that because anything squared is greater then 0 it was correct. doubt ill get the marks though.

I hope they don't castrate us w/ Paper 2 to balance it out.

SantryRed

What is the answer to Q1(b)?

Is 16p^2 +1>0 correct?

As that's a ture statement which proves the roots are real?

EuropeanSon

SantryRed wrote: »

What is the answer to Q1(b)?

Is 16p^2 +1>0 correct?

As that's a ture statement which proves the roots are real?

Yes.

zam

SantryRed wrote: »

What is the answer to Q1(b)?

Is 16p^2 +1>0 correct?

As that's a ture statement which proves the roots are real?

Well I said 16p^2 > -1
But I'm sure your answer merits the bulk of the marks!

SantryRed

SantryRed wrote: »

What is the answer to Q1(b)?

Is 16p^2 +1>0 correct?

As that's a ture statement which proves the roots are real?

Yeah, as far as I can see because p is squared it will always be greater than 0 (or -1 if you moved that over like me).

EuropeanSon

zam wrote: »

Well I said 16p^2 > -1
But I'm sure your answer merits the bulk of the marks!

It merits all of them. It's the exact same answer as yours. A true statement is a true statement, and that's all that's needed. I said 1>0 and 16p^2>=0 too, but that was just overkill on my part.