How do you find the zeros, real and imaginary, of y=-x^2-4x-11 using the quadratic formula?

1 Answer
Jul 4, 2017

2 imaginary roots:
x = - 2 +- isqrt7

Explanation:

y = - x^2 - 4x - 11 = 0
Use the improved quadratic formula in graphic form (Google Search)
D = d^2 = b^2 - 4ac = 16 - 44 = - 28
Since D < 0, there are 2 imaginary roots.
d = +- 2isqrt7
x = -b/(2a) +- d/(2a) = 4/-2 +- 2isqrt7/2 = - 2 +- isqrt7