What value should be added to the expression to create a perfect square?
a. 64
b. 4
c. 16
d. 8

Let's take a look at a perfect square trinomial.



We can distribute this expression to get .

An important relation to recognize here is that the constant is the square of half of the x value.

Now, if we wanted to add a number to to make a perfect square trinomial, we could have the value of x and then square it.

Half of 16 is 8, and 8 squared is