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# OCR MEI C3 Maths June 2015 watch

1. sin(x + π) = -sin(x) ?

Someone tell me how this is?
2. Can someone help me with this question

its from june 2009
Having trouble with part ii
thx

xxx
3. (Original post by Hody421)
sin(x + π) = -sin(x) ?

Someone tell me how this is?
Just consider the period of the sin graph.
4. (Original post by emi1996)
Can someone help me with this question

its from june 2009
Having trouble with part ii
thx

xxx
Replace the second bracketed term in part A with the result found part B.
5. (Original post by Hody421)
sin(x + π) = -sin(x) ?

Someone tell me how this is?
there you go!
Attached Images

6. (Original post by emi1996)
Can someone help me with this question

its from june 2009
Having trouble with part ii
thx

xxx
If x > y then x – y > 0
(x + 0.5y)^2+ (3/4)y^2is greater than 0 since it is the sum oftwo squares
so x^2+ xy + y^2 > 0
Therefore (x – y)(x^2+ xy + y^2) > 0

So x^3– y^3> 0
i.e. x^3> y^3
7. Ive been put in for the core 3 exam early and have no clue what im doing frustrated cuz ill definately need to retake next year
8. (Original post by lizard54142)
Just consider the period of the sin graph.
what is the period of a sin, cos and tan graph?
9. http://www.thestudentroom.co.uk/atta...hmentid=425525

Anyone know what exam paper that is from?
10. (Original post by messupp)
If x > y then x – y > 0
(x + 0.5y)^2+ (3/4)y^2is greater than 0 since it is the sum oftwo squares
so x^2+ xy + y^2 > 0
Therefore (x – y)(x^2+ xy + y^2) > 0

So x^3– y^3> 0
i.e. x^3> y^3
Thx!
11. How do you know when to use integration by substitution? Is there a rule or do you just use it when you don't think any other method would work?

e.g. how would you know to use substitution for this: (or is there another method that works for this Q?)

12. what is the period of a sin, cos and tan graph?

13. http://www.thestudentroom.co.uk/atta...hmentid=425525

Anyone know what exam paper that is from?
Jan 2012
14. (Original post by tingirl)
How do you know when to use integration by substitution? Is there a rule or do you just use it when you don't think any other method would work?

e.g. how would you know to use substitution for this: (or is there another method that works for this Q?)
You can actually integrate this directly (because it is a linear function in the square root), so you don't need to use a substitution if you don't want to. Rewrite it as
15. (Original post by lizard54142)

There was a question that wanted you to state an actually answer like 180 degrees??

16. There was a question that wanted you to state an actually answer like 180 degrees??
Yeah, I just told you the periods!

Tangent has a period of or 180 degrees, Sine and Cosine both have a period of or 360 degrees.
17. (Original post by lizard54142)
You can actually integrate this directly (because it is a linear function in the square root), so you don't need to use a substitution if you don't want to. Rewrite it as
OH YEAH!!! Thanks! I think I get it now - if there was a fraction with in the denominator and no in the numerator, you'd use substitution, right?
I hope they just tell us when to use substitution
18. (Original post by tingirl)
OH YEAH!!! Thanks! I think I get it now - if there was a fraction with in the denominator and no in the numerator, you'd use substitution, right?
I hope they just tell us when to use substitution
From doing past papers they do seem to tell you if you need to do a substitution but this doesn't mean they always will! If the function being integrated looks like something you might use the chain rule on to differentiate, you might want to consider a substitution.
19. (Original post by Hody421)
sin(x + π) = -sin(x) ?

Someone tell me how this is?
Its a sin graph shifted 180 degrees to the left, so its a negative sign graph. Try drawing it or visualizing it being shifted to the left
20. Good luck everyone. This should be our easiest exam so let's smash it....

...then worry about C4 later ;D

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