Re: MX2 2015 Integration Marathon
Can you really make that substitution when clearly cot 0 is undefined?
Also, can you show ur working for how you went from the trig to the u bit? I don't think ur integrand is quite right....
Re: 2015 permutation X2 marathon
non invertible, but you still can't use the conventional method of arranging n distinct elements around a circle, then account for repetitions. For instance, consider the problem how many ways can you arrange AAABBB around a circle? Using the conventional method...