We need to add and subtract the same number in the expression so we can write it as a square and a constant, as in the following expression:

The given expression is:

In order to find the number that must be added and subtracted, let's expand the general expression:

Comparing the coefficients of the general and the given expression, we have:

So, using a = 1, h = 1, and k = -3, we can write:

Notice that we obtain the same result by adding 3-3 to the original expression:

Therefore, the answer is:
