Question

If there is only one solution to the equation 0=-x^2 + bx -8 what are the possible values of b?

Answer 1

`b = 4√(2)`,
`b = -4√(2)`

Explanation:

For a single solution, you must have a perfect square trinomial.

`-x^2 + bx - 8 = 0`

`x^2 - bx + 8 = 0`

`(x - √(8))^2 = 0`

`x^2 - 2√(8)x + 8 = 0`

`x^2 - 4√(2)x + 8 = 0`

`-x^2 + 4√(2)x - 8 = 0`

`b = \pm 4√(2)`