Question

the only solution of the equation $x^2 + bx + 16 = 0$ is $x = 4$. what is the value of $b$?\
\bigcirc $b = -16$\
\bigcirc $b = -8$\
\bigcirc $b = 8$\
\bigcirc $b = 16$

Explanation:

Step1: Substitute x=4 into equation

$4^2 + b(4) + 16 = 0$

Step2: Simplify the left-hand side

$16 + 4b + 16 = 0$
$32 + 4b = 0$

Step3: Solve for b

$4b = -32$
$b = \frac{-32}{4}$

Answer:

b = -8