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

Ok so you were right BUT in this case it was testing your ability to manipulate indices (the question said put it in the form p x q^n NOT p x q^(n-1).

so have a look at the image below that i have made to explain what to do, excuse that it has been done in paint and let me know if you need further help

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

Hey. I have done a bunch of questions, and while I did get them all correct, I used a different method to what is specified in the mark scheme (I used the binomial formula method and made it (1+ax)^n rather than nCr like is taught at C2). Would I still get full marks for this or would I lose the working marks?

Please expand upon what you mean because im not fully understanding how you have written it :P

Yeah sure what is the problem you experience with them when doing these types of questions?

So you are aware of binomial expansions? There are two methods of finding the coefficients, nCr and the expansion formula ( 1 + nax + (n(n-1)(ax)^2)/2! ........). The mark schemes I have read relating to questions like (2 - 3x)^5 or whatever only specify solutions based off of nCr, whereas I have used the expansion formula and have removed the 2 by going 2^5(1 - 3/2x)^5 as learned in C4. Would I get full marks using the unspecified formulae or would I have to use nCr in order to get full marks?

defo, my teacher taught me that way for C4 as well and taught the C2 year 12's to use that one so im sure its valid!

So you are aware of binomial expansions? There are two methods of finding the coefficients, nCr and the expansion formula ( 1 + nax + (n(n-1)(ax)^2)/2! ........). The mark schemes I have read relating to questions like (2 - 3x)^5 or whatever only specify solutions based off of nCr, whereas I have used the expansion formula and have removed the 2 by going 2^5(1 - 3/2x)^5 as learned in C4. Would I get full marks using the unspecified formulae or would I have to use nCr in order to get full marks?

just gone over optimisation still hate it..

thankyou

Oh hey so basically its obviously just like differentiation but in the form of physical shapes e.g cubes or cylinders. Now i think its pretty easy. You just have to ask yourself what the formula of volume or surface area is e.g. for a cube lets say. Break it down! What is the surface area? Well its the area of 6 different faces; top/bottom, left/right and front/back.

A random variable e.g. 2x is assgined to each of the length, width and depth so just take a step back and think about it. Work out the area of each of the 3 types of face and multiply the area by 2 because there are 2 for each type, e.g if the height is h and the length of the cube is 2x then the area of that one face is 2xh but you have one on the other side so it becomes 4xh. When you have done this for all faces they normally tell you the numerical value of the surface area or whatever it is so just add together all the algebraic terms of the surface area and set that equal to the numerical value.

Then they may ask you to find V (volume) or whatever but DONT let it put you off by asking you to put it in an unfamiliar form. For now just concentrate on manipulating the area to get the formula for V. Sometimes they ask you to put V in a form that doesn't involve one of the variables, e.g. without h (only numbers and x's) so just rearrange the above equation to make h the subject and then sub this rearranged formula into the V formula.

After this they may ask you to calculate dV/dx or whatever but dont be put off by this, think of v as y like in dy/dx and then it becomes easy differentiation. They then might ask to verify a minimum/max point at x = whatever but this is easy once you know that dv/dx at a certain point = 0. I hope this is clear and that this has at least marginally helped you, let me know how you get on with it and dont give up

I get confused with cos graphs 😒