#### Answer

b = 8 or b = -8

#### Work Step by Step

In a perfect square trinomial, in th form $ax^{2} + bx + c$, the constant (c) is equal to the square of half the coefficient of the second term, b.
$c = (\frac{b}{2})^{2}$
Substitute c with 16 and solve for b.
$16 = (\frac{b}{2})^{2}$
To undo the square, we need to take the square root of 16, which will equal to either positive 4 or negative 4. In this case, we will split this off into two equations to solve for the two possible values for the second term coefficient.
$4 = \frac{b}{2} $ and $ -4 = \frac{b}{2}$
Solve for b by multiplying both sides of the equation by 2.
b = 8 and b = -8