The only solution of the equation x2 + bx + 16 = 0 is x = 4. What is the value of b?

b = - 16

b = - 8

b = 8

b = 16

To factor out x2 + bx + 16, the easiest way is to find out 2 different values that will add up to b but when multiplied is positive 16. Given that the only solution to this equation above is x = 4. the factored out form should be (x - 4) ^2 or (x-4) (x-4). As b should be the addition of these two x values, b should be - 8. The correct option is the second option, b = - 8.