What constant term is necessary to complete the perfect square trinomial pictured in the algebra tiles?
x2 + 8x +

The algebra tiles show two equal factors. They are (x + 4).

Then, the perfect square is the product of the two equal factors, (x + 4) * (x +4).

That is (x + 4)^2.

Then develop that perfect square to find the constant term.

(x + 4)^2 = x^2 + 8x + 16.

That means that the constant term needed to complete the trinomial is 16.

16