A binomial square have the following form:
So, from the coefficient of the second term, we can get the value a and with the value a we can calculate a² for the value of the third term, that is, the value we need to add to make it a perfect square.
We have the expression:
By comparing the second terms, we see that:
Since we have a, we can calculate a²:
So, this means the number we need to add is 49 and, since a is 7, the trinomial can be rewritten as:
So, add 49 and the square binomial is: