I'm studying for my Maths A-level by doing past exams. However, while I generally answer the questions well enough, I seem unable to do them all within the time limit, generally missing one-two on average. I'm not used to showing my work and as I'm home-educated I do not have anyone to tell me what work the exam markers want me to show. But for the mock exams I've been trying really hard to show every step. I'm also trying to write neater (my handwriting isn't normally good). However, this means that I might be wasting some time. Can anyone give an opinion on what sort of working I can discard? I'll give an example below. It's a small example, but the larger questions all have graphs I cannot write down here.
This is from the Edexcel GCE Core Mathematics C2 Advanced Subsidiary, Friday 13 January 2012 - Morning (this is essentially all the big words on the front page).
2. A circle C has centre (-1, 7) and passes through the point (0, 0). Find an equation for C.
Equation of circle = (x - a)2 + (y - b)2 = r2, where x = x-coordinate of centre, y = y-coordinate of centre and r = radius.
(x - (-1))2 + (y - 7)2 = r2
(x + 1)2 + (y - 7)2 = r2
(0 + 1)2 + (0 - 7)2 = r2
12 + (-7)2 = r2
1 + 49 = r2
r2 = 50
answer:
(x + 1)2 + (y - 7)2 = 50