x^2 + 8x + 17 = 0
Use equation ax^2 + bx + c = 0
then put numbers into quadratic formula
x = (-b +/- (b^2 - 4ac)^(1/2)) / 2a
And so in this case
a=1 b=8 c=17
x = ((-8 +/- (8^2 - 4 x 1 x 17)^(1/2)) / (2 x 1)
x = ((-8 +/- (64 - 68)^(1/2)) / 2
x = -2 +/- ((-4)^(1/2)) / 2
x = -2 +/- (2i) / 2
so x = - 2 + i and x = - 2 - i
where a = - 2 and b = -1, 1