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AQA Core 2 Maths prep. thread (25/05/16) Watch

1. (Original post by RueXO)
I get confused with cos graphs 😒
Ah ok what is it that confuses you? Y values are between 1 and -1 and the periodicity is 360 degrees. Or is it the finding other values within the domain that you find difficult?
2. (Original post by Rager6amer)
Ah ok what is it that confuses you? Y values are between 1 and -1 and the periodicity is 360 degrees. Or is it the finding other values within the domain that you find difficult?
Finding other values, I sometimes end up missing some of them, and it's not as easy as sine graphs. I don't get when to add 180 or 360, when to take away etc
3. (Original post by RueXO)
Finding other values, I sometimes end up missing some of them, and it's not as easy as sine graphs. I don't get when to add 180 or 360, when to take away etc
Does this diagram i quickly made help? When the green line intersects the graph the blue lines are obviously where your solutions are (but of course it depends on the domain and if the graph has been transformed). Have a look at the example where cos x = 1/2 and then see how it is done. Let me if this helps/ if ya still stuck and at p.s i hope you are not colour blind lol :P
Attached Images

4. Does anyone know whether we have to be able to derive the formulas for all of the geometric and arithmetic progressions?
5. (Original post by Kingal001)
Does anyone know whether we have to be able to derive the formulas for all of the geometric and arithmetic progressions?
Definitely not.

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6. (Original post by Kingal001)
Does anyone know whether we have to be able to derive the formulas for all of the geometric and arithmetic progressions?
Are you joking? What rock have you been living under...
7. (Original post by Adam998)
Are you joking? What rock have you been living under...
Does this mean yes or no?
And I would hope a nice rock.
8. (Original post by Kingal001)
Does anyone know whether we have to be able to derive the formulas for all of the geometric and arithmetic progressions?
Edexcel make you do it but aqa never has so i would hope not but im gonna prepare for it anyway cos you never know
9. I think I did okay on Core 1, although I admit the paper was horrible (I was pretty prepared though because I did all the past papers so pretty much knew how to answer most things, just I might have made mistakes on the dodgy numbers) I'm still annoyed with 45 x 7 and the minimum point being -41/4 but I guess aqa hates us lol

I saw on a past paper that you had to make a geometric sequence in to the nth term one. I looked at the mark scheme but it didn't help much (I got 1 mark out of 2 because I could make it in to Un= just not N=)
How do you make a geometric sequence and arithmetic sequence (just in case lol) in to a Nth term sequence (I'm not sure if i explained that well, but like trying to get rid of the r^(n-1) to just r^n)

Thank uuuu
10. (Original post by GoldenLotus)
I think I did okay on Core 1, although I admit the paper was horrible (I was pretty prepared though because I did all the past papers so pretty much knew how to answer most things, just I might have made mistakes on the dodgy numbers) I'm still annoyed with 45 x 7 and the minimum point being -41/4 but I guess aqa hates us lol

I saw on a past paper that you had to make a geometric sequence in to the nth term one. I looked at the mark scheme but it didn't help much (I got 1 mark out of 2 because I could make it in to Un= just not N=)
How do you make a geometric sequence and arithmetic sequence (just in case lol) in to a Nth term sequence (I'm not sure if i explained that well, but like trying to get rid of the r^(n-1) to just r^n)

Thank uuuu
11. (Original post by RueXO)
Finding other values, I sometimes end up missing some of them, and it's not as easy as sine graphs. I don't get when to add 180 or 360, when to take away etc
I will try to explain it as best as I can, I'm doing A2 and retaking c2 to bump my grade to a high A hopefully.
So you have your equation, lets say sin x =0.5, you will do sin^-1 (0.5) to get what x equals, in this case it's 30 degrees.
Now we draw our cast diagram, 4 quadrants, the number is positive and sin, therefore we will use the 'ALL' quadrant and the SINE quadrant only. Draw a line an angle, it doesn't need to be exact or anything, just a representation in each quadrant, the angle you're looking at is between this line and the horizontal x line. Now every single time you do this method, always remember you start from the middle right (3 o'clock position on a clock) and go anticlockwise until you reach a point you have drawn on. So the first time you do that, you will hit the line you drew in the ALL quadrant which is 30 degree's, this is your first value. Then start again till you get to your next line, you know this line will be 180-the angle which is 30, so 180-30=50. Now you have your 2 values. Majority of the time, this will be the only 2 you need, however, if the range is very high, all you have to do is plus or minus 360 onto either of these, if they still fit in the range, these are valid values
.This picture I just drew of that problem might help.

For minus values, it's slightly different, however, the only difference is when drawing your lines onto the cast diagram you do the OPPOSITE quadrants to what it would be. So a minus sine value, you would draw your lines into the COS and TAN quadrant then repeat the exact same process as before.
Attached Images

12. (Original post by CheaterHater)
I will try to explain it as best as I can, I'm doing A2 and retaking c2 to bump my grade to a high A hopefully.
So you have your equation, lets say sin x =0.5, you will do sin^-1 (0.5) to get what x equals, in this case it's 30 degrees.
Now we draw our cast diagram, 4 quadrants, the number is positive and sin, therefore we will use the 'ALL' quadrant and the SINE quadrant only. Draw a line an angle, it doesn't need to be exact or anything, just a representation in each quadrant, the angle you're looking at is between this line and the horizontal x line. Now every single time you do this method, always remember you start from the middle right (3 o'clock position on a clock) and go anticlockwise until you reach a point you have drawn on. So the first time you do that, you will hit the line you drew in the ALL quadrant which is 30 degree's, this is your first value. Then start again till you get to your next line, you know this line will be 180-the angle which is 30, so 180-30=50. Now you have your 2 values. Majority of the time, this will be the only 2 you need, however, if the range is very high, all you have to do is plus or minus 360 onto either of these, if they still fit in the range, these are valid values
.This picture I just drew of that problem might help.

For minus values, it's slightly different, however, the only difference is when drawing your lines onto the cast diagram you do the OPPOSITE quadrants to what it would be. So a minus sine value, you would draw your lines into the COS and TAN quadrant then repeat the exact same process as before.
Nice one, thanks for sharing
13. Okay, this is probably going to sound like a stupid question but I'm having a bad day;

Can anyone see where I've gone wrong with this?

The question is: Expand (1+sqrt x)^3
So I did (1+sqrt x)^2 which was 1+x+2sqrtx
and then (1+sqrt x)(1+x+2sqrtx) to get 1+3x +3xsqrtx

Sorry like I say, it's not a good day
14. (Original post by Blake Jones)
Okay, this is probably going to sound like a stupid question but I'm having a bad day;

Can anyone see where I've gone wrong with this?

The question is: Expand (1+sqrt x)^3
So I did (1+sqrt x)^2 which was 1+x+2sqrtx
and then (1+sqrt x)(1+x+2sqrtx) to get 1+3x +3xsqrtx

Sorry like I say, it's not a good day
The answer is 1 + 3√x + 3x + x^(3/2)

But might i suggest using binomial expansion instead? Its much quicker. Like ok for brackets ^3 its not to bad but like to the ^4 or ^8 come on? Practice binomial expansion formula which is much more effective, i assume you are familiar with it?
15. (Original post by Rager6amer)
The answer is 1 + 3√x + 3x + x^(3/2)

But might i suggest using binomial expansion instead? Its much quicker. Like ok for brackets ^3 its not to bad but like to the ^4 or ^8 come on? Practice binomial expansion formula which is much more effective, i assume you are familiar with it?
Yeah I need a bit of practise at the binomial expansion, expanding brackets is more in my safe zone so I tend to stick to that where reasonable, thank you though
16. (Original post by Rager6amer)
Jan 2013
6. a) A geometric series begins 420 + 294 + 205.8
iii) Write the nth term of the series in the form p x q^n

As far as I got was Un=420x0.7^(n-1) which got me 1 mark (out of 2)
17. Okay, this will probably sound like another silly question but please bear with me, like I say today is tough going but I'm trying my best.

In one question I'm looking at they've got (cos^2x + 4sin^2x) / cos^2x = 7 which I understand how they get that from the previous line but then the next line they have is 1+ (4sin^2x / cos^2x) = 7 which I don't understand, I get that cos^2x + sin^2x = 1 but surely by this logic if you were going to replace the cos on the top line you'd have to put 1-sin^2x wouldn't you? And surely 4sin^2x - sin^2x = 3sin^2x not 4?

Sorry if this is obvious,
Blake
18. The thing I struggle with most in core 2 is the logarithms questions, anyone have any advice on how to tackle them as they're usually worth lots of marks? oh and I always get the transformations confused too
19. (Original post by Blake Jones)
Okay, this will probably sound like another silly question but please bear with me, like I say today is tough going but I'm trying my best.

In one question I'm looking at they've got (cos^2x + 4sin^2x) / cos^2x = 7 which I understand how they get that from the previous line but then the next line they have is 1+ (4sin^2x / cos^2x) = 7 which I don't understand, I get that cos^2x + sin^2x = 1 but surely by this logic if you were going to replace the cos on the top line you'd have to put 1-sin^2x wouldn't you? And surely 4sin^2x - sin^2x = 3sin^2x not 4?

Sorry if this is obvious,
Blake
All they have done is split the fraction. So from what they give you, you can now split it to be cos^2x/cos^x which is where they get there 1 value from and then what's left is 4sin^2x/cos^x
20. (Original post by CheaterHater)
All they have done is split the fraction. So from what they give you, you can now split it to be cos^2x/cos^x which is where they get there 1 value from and then what's left is 4sin^2x/cos^x
Thank you so much, I get that now

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