Edexcel A2 C3 Mathematics 12th June 2015

Original post by Gome44

X^2 + 3 is always positive anyway, so you can just remove the mod sign :smile:

Ok, what if it was:

|x^2 - 36| + 2x

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Reply 1083

gameofthrones1

Original post by Medicjug

Someone pleaseeeeeee helpppp ImageUploadedByStudent Room1433887920.628872.jpg

a) Use the double angle formula to expand Rcos(x-#) (pretending # is alpha):L

Rcos(x - #) ---> Rcosxcos# + Rsinxsin#

Take coefficients of cosx and sinx:

Rcos# = 1 and Rsin# = ROOT(3)

Since Rcos#/Rsin# ----> tan# (where R cancels out)

-> tan# = Root(3)/1

solve tan^-1(root(3)/1) to get your value for #. # = (pie)/3

To find R -----> R^2 = 1^2 + (root(3))^2
R = root(4) = 2
Leave in the form - 2cos(x - (pie)/3) where you have a value for # as (pie)/3

b) Use your values in part a) to solve b)! Very much like C2!!

Hope this helps!!

(edited 8 years ago)

Reply 1084

Gome44

10

Original post by it's a me, mario

Ok, what if it was:

|x^2 - 36| + 2x

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Doubt this will ever come up, but here's how I would do it:

Consider when the inside of the | | sign is negative. This is when -6<x<6. A property of the mod sign is |y| =-y when y<0. In this case y=x^2 -36. So from -6<x<6, the curve you need to sketch is -(x^2 -36) +2x, and for the other parts you need to sketch x^2 -36 +2x

Reply 1085

Gome44

10

Original post by Medicjug

Someone pleaseeeeeee helpppp ImageUploadedByStudent Room1433887920.628872.jpg

I assume you've done the first part? In the second, you should end up with cos(2x-α)-cos(x)=0

What teeEm has done in the solutions is use the periodicity of cos, however, you can also write this in an alternate form using factor formula (in the formula book)

(edited 8 years ago)

Reply 1086

Original post by Cowy97

the first part r= sqrt(1^2+sqrt3^2)
and a tan^-1 (sqrt3/1)
i think
and i would be ****ed if b came up in the exam

if only.. many would ...

Reply 1087

Original post by Medicjug

Someone pleaseeeeeee helpppp ImageUploadedByStudent Room1433887920.628872.jpg

Not for the faint hearted ...

Reply 1088

gcsestuff

Original post by TeeEm

if only.. many would ...

Teeem are you a student or a teacher

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Reply 1089

Original post by gcsestuff

Teeem are you a student or a teacher

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neither ...

Reply 1090

vuvuzela

3

Can someone confirm that integration and implicit differentiation are not part of edexcel C3. Thanks.

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Reply 1091

Original post by vuvuzela

Can someone confirm that integration and implicit differentiation are not part of edexcel C3. Thanks.

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confirmed

Reply 1092

gcsestuff

Original post by TeeEm

neither ...

Are you an examiner?

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Reply 1093

Original post by gcsestuff

Are you an examiner?

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I am a mathematician

Reply 1094

s234590

3

Original post by TeeEm

I am a mathematician

can you help me with domain and range please?

Reply 1095

Original post by s234590

can you help me with domain and range please?

I will be if you have a specific question when I get back from my morning walk
(about 1 hour)

Reply 1096

vuvuzela

3

Original post by TeeEm

confirmed

Thanks so much

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Reply 1097

Nurishment

Original post by Medicjug

Someone pleaseeeeeee helpppp ImageUploadedByStudent Room1433887920.628872.jpg

Which IYGB paper is that?

Reply 1098

Medicjug

Original post by Nurishment

Which IYGB paper is that?

I think it's p

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Reply 1099

Medicjug