Question

How do you solve `2x^2 - 5x – 10 = 0` using the quadratic formula?

Answer 1

`(5 +- sqrt105)/4`

Explanation:

Use the improved quadratic formula (Google, Yahoo Search)
`y = 2x^2 - 5x - 10 = 0`
`D = d^2 = b^2 - 4ac = 25 + 80 = 105` --> `d = +- sqrt105`
There are 2 real roots:
`x = -b/(2a) +- d/(2a) = 5/4 +- sqrt105/4 = (5 +- sqrt105)/4`