Question

Which of the following is a solution of x2 + 2x + 8?

Answer 1

Using the quadratic equation we get:
$\frac{ - 2 + - \sqrt{4 - 32} }{2} = \frac{ - 2 + - \sqrt{ - 28} }{2}$

Factoring out 2 we get
$\frac{ - 2 + - 2\sqrt{ - 7} }{2} = - 1( + - ) \sqrt{ - 7}$
Factoring out the imaginary number:
$- 1 + \sqrt{7} i \: (and) \: - 1 - \sqrt{7} i$
So b.