I'll teach you an easy way to do this.
Since you already have your polynomials and their equations all you need to do is multiply the polynomial to find it's original.
So here just look: (x+3)(x-2) Multiply x by the values in the other part to get x^2 and -2x. Now do the same with 3 to get 3x and -6.
Put this in an equation now, and assuming you did it right, it will look something like this: x^2+3x-2x-6.
Now simplify to get x^2+x-6. Just do that for the rest now.