Question

How do you solve `x^2 + 3 = 9x` using the quadratic formula?

Answer 1

`x = (9 +- sqrt69)/2`

Explanation:

`y = x^2 - 9x + 3 = 0.`
Use the improved quadratic formula (Google, Yahoo Search).
`D = d^2 = b^2 - 4ac = 81 - 12 = 69` --> `d = +- sqrt69`.
There are 2 real roots:
`x = -b/(2a) +- d/(2a) = 9/2 +- sqrt69/2 = (9 +- sqrt69)/2`