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OCR Core 2 Maths: Wednesday 25th May 2016

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what did everyone get for the period question too?
Did anyone get 38 for the summations sequences question and X=12,-3 for logs
i think it's only x=12, -3 wasn't possible
Original post by M12345689
Did anyone get 38 for the summations sequences question and X=12,-3 for logs


For some reason i got 37 for the summation i might have made a slip up some where. I got the same for the logs
Original post by Stanspam
i think it's only x=12, -3 wasn't possible


I thought because the X was squared it would make it possible as it would go to 9
Original post by Stanspam
i think it's only x=12, -3 wasn't possible


-3 was possible if you put it into the equation the bit inside the log was >0 as there was x^2 and x+4
Reply 26
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Csd1999
1
Does anyone remember what the actual log question was?
Reply 27
Avatar for h3rmit
h3rmit
15
Original post by Csd1999
Does anyone remember what the actual log question was?


2log x - log (x+4) = 3, I think

Edit: scratch that, guy below me is right
(edited 7 years ago)
Original post by Csd1999
Does anyone remember what the actual log question was?


2log base 3 (X) - log base 3 (X+4) = 2
I think
Reply 29
Avatar for h3rmit
h3rmit
15
Original post by sandpitturtle
what did everyone get for the period question too?


I got pi/a, just by trying sin x, sin 2x, sin 3x, etc and roughly sketching the graph.

Original post by M12345689
Did anyone get 38 for the summations sequences question and X=12,-3 for logs

Yep, I got that.

Original post by Stanspam
i think it's only x=12, -3 wasn't possible
-3 is possible because you square the x on top and add 4 to x on the bottom, so you get x^2 / 1
Original post by h3rmit
I got pi/a, just by trying sin x, sin 2x, sin 3x, etc and roughly sketching the graph.


Yep, I got that.

-3 is possible because you square the x on top and add 4 to x on the bottom, so you get x^2 / 1


-3 wasn't possible in the original equation
Reply 31
Avatar for h3rmit
h3rmit
15
Original post by Annonomous09
-3 wasn't possible in the original equation


It is if
Original post by M12345689
2log base 3 (X) - log base 3 (X+4) = 2

is the original equation, which does definitely seem to ring a bell. If you apply the 2 as a power before logging it works and gives 2
Unofficial mark scheme anyone?
Reply 33
Avatar for Csd1999
Csd1999
1
Does anyone know how many marks the log question was worth?
Original post by h3rmit
It is if

is the original equation, which does definitely seem to ring a bell. If you apply the 2 as a power before logging it works and gives 2


I don't think it counts as you can't really square a minus, and log isn't valid for negative numbers, but I am not tottaly sure
Was the period not 2pi/a?
Original post by sandpitturtle
I don't think it counts as you can't really square a minus, and log isn't valid for negative numbers, but I am not tottaly sure


Why cant you square a minus? Surely it works like squaring in general, turns it positive? Maybe they wanted you to state it would have to be 3 instead of -3?
(edited 7 years ago)
Original post by Sourestdeeds
Why cant you square a minus? Surely it works like squaring in general, turns it positive? Maybe they wanted you to state it would have to be 3 instead of -3?


true, sorry i got confused with sqr rooting, i am still so unsure about that question if -3 was counted though
either way would probably only be a mark so not too fussed haha
Original post by sandpitturtle
true, sorry i got confused with sqr rooting, i am still so unsure about that question if -3 was counted though
either way would probably only be a mark so not too fussed haha


I was also confused because it works in the rearranged equation, just not the original. I just stuck with 12 anyway
What do people think the boundaries will be?

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