Re: HSC 2013 4U Marathon
1.
P'(x) = (2x-(a+b))g(x) + g'(x) (x-a)(x-b)
If a and b are consecutive roots, then it is easy to see that P'(a) and P'(b) are opposite in sign by drawing a picture. They can't be zero since they have roots of multiplicity of 1.
P'(a) = (a-b) g(a)
P'(b) = (b-a)...