10 is C.
Use formula, and then group terms containing x on one side then use difference of two squares to factorise and expand easily. Divide both sides by -4, to get b(x-a) = a(y-b) which simplifies to bx = ay
1. D - angle at centre, twice angle at circumference
2. A - use auxiliary angle formula
3. C - use x^r (x^-3(12-r)) form
5. B - A and C are wrong because product of roots is -42, and D is obvious wrong
6. B - use standard integral sheets and times by 3
7. A - write in A sin (nt) form for x and then differentiate. Note p = 2pi/n
8. D - not really sure why 15!x5!/(9! x 6!) i.e. 15C6 x 5!
9. C - sub P(-1)
10. C - expand out to bx = ay i.e. C