Question

How do you find the x intercepts for `f(x) = -x^2 + 6x + 8`?

Answer 1

To find x-intercepts, make y = 0. Solve f(x) = 0

-x^2 + 6x + 8 = 0
`D = d^2 = 36 + 32 = 68 = 4(17) -> d = +- 2sqrt17.`

`x = -b/(2a) +- d/(2a) = 2 +- sqrt17`