1. The problem statement, all variables and given/known data 1) If I know that z_1 = (2+i) and z_2 = (2-i) are solutions to a polynomial, how do I find it? (I have six to chose between, it's a multiple choice). Do I just insert and see of it equals zero? 2) When I know that z^2 has modulus 4 and argument pi/2, how do I find modulus and argument for z? 3) If I know a polynomial (real numbers, not complex!) f(x) = 2x^2 and g(x) = cx, how do I find the number c, so g(x) is a tangent to the polynomial? 3. The attempt at a solution 1) I would just insert solutions. 2) I do not know how to approach this problem. 3) First, g(x) = f(x), and the gradient of g(x) must equal f'(x) in the point x_0?