1. If A, b, and c are the roots of the equation 2x^3-6x^2-15x-3=0, then find (1/(a^2)) + (1/(b^2)) + (1/(c^2))
2. Let a, b, c be the roots of the equation 2x^3+4x^2-5x-3=0. Build a cubic equation which has roots ab, bc, ac
3. The polynomials x^3-ax^2-2x-1 and x^3-3x-2 have a common root. Find all possible values of a.