In fact, this is a trinomial of the form , whose solutions are given by Using this formula for the trinomial of the problem, we find: <span>we see that this trinomial has two coincident solutions (x=3 with multiplicity 2). This means that it can be rewritten as a perfect square, in the following form: </span><span> </span>
In order to solve this you just have to try and factorize the options and the result should be two exact binomials. Remember that the formula for perfect square trinomial is: