f(x) = x
2 + 2
y = x
2 + 2 (rewrite f(x) as y)
x
2 + 2 = 0 (set quadratic equation to zero)
Standard form of quadratic equation:
ax
2 + bx + c = 0
Use quadratic formula to solve:
x = (-b +/- (b
2 - 4ac)
1/2 ) / 2a
Coefficients (a,b,c) for x
2 + 2 = 0:
a = 1; b = 0; c = 2
Plug in coefficients (a,b,c) into quadratic formula and solve:
x = (-0 +/- (0
2 - 4(1)(2))
1/2) / 2(1)
x = +/- (-8)
1/2 / 2
x = +/- (4)
1/2(2)
1/2(-1)
1/2 / 2
x = +/- 2(2i) / 2
There are 2 imaginary roots (zeroes) of our function, f(x) = x
2 + 2: +2i and -2i