i) write down the expression of a 4th degree polynomial using for example a, b, c, d, e as the various coefficients
ii) use the equations given, differentiating if necessary, to set up a system of 5 equations in a through e.
iii) use whatever method you like, or are instructed to, to solve these equations.
iv) write your polynomial using the coefficients just solved for
v) bask in glory