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

Does anyone know whether we have to be able to derive the formulas for all of the geometric and arithmetic progressions?

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

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.

please link me the question.

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)

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)

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

so it wants you to write q^n, you have written q^(n-1). The first value is 420, therefore the equation will become. 420=p x 0.7^1. Re-arrange and p=600, so the answer should be un=600 x 0.7^n
Is that correct?
Sometimes you need to think less about the equations they give you and logically about the question.

Logs are difficult but the key is just knowing that you have a toolbelt with about 10 log laws so just always see what the examiner has done to try and muddle up the logs and so just do a small step at a time (e.g. simplify log a - log b to log a/b etc)

Its difficult to explain without context, so if you were to choose a question/example that you found difficult I would be more than happy to help

Considering the fact that I've studied A2 maths and further maths. I feel quite confident in the C2 paper. The only that still catches me are the Arithmetic and Geometric progressions. Does any body know an effective way of practic8ng these so they fit in my head.

This question was from 2014 and I don't know how to do c and d?

Part C: whenever you have a translation, you write the opposite of what you do in into the equation, for example if i have the line y = 6x + 4 and I translate it by vector (-2,0) I have moved it 2 units to the left BUT in the equation I replace 'x' with 'x+2' so therefore the new one would be y = 6(x+2) + 4 so it would become y = 6x +12 +4 so therefore y = 6x +16 (i hope this makes sence)

So to answer the question in part C you have translated it by (1,p) so remember we write the opposite so therefore y = 3 x 12^x becomes 'y-p = 3 x 12^(x-1)' and so rearrange to get y = 3 x 12^(x-1) + p now since the curve intersects the origin (0,0) we can sub in the values 0 and 0 for x and y so then we get 0 = 3 x 12^(0-1) + p and so therefore 3 x 1/12 + p = 0 so rearrange to get 1/4 + p = 0 and hence p = -1/4. I hope this makes sense.

As for the logs it would take forever for me to explain so check out the written solution here and see if this makes sense. let me know if you have any more problems http://bit.ly/1RhsgoK

Try this geometric progression question. It's a question I remember from one of Teeem's threads a while back now.

thankyou