Find dy/dx for the following:

a) y=3x^2 - 3x
b) y=x^3(3+5x)^2
c) y=(x^2+1)^2/2x

Please offer your help as I urgently need help

Just recall the power rule.

y = x^n
y' = n x^(n-1)

(a) y' = 3(2x)-3(1) = 6x-3
For (b) and (c), just expand the polynomials, do the division as required, and then apply the power rule for each term