What is b if y= x^2 + 3x + b has two complex roots.?

Given the quadratic equation
:

y= x^2 + 3x + b

We need to
determine b such that y has two complex roots.

We know that
if delta < 0, then the quadratic equation has 2 complex
roots.

==> delta = b^2 - 4ac <
0

==> a = 1   b= 3    c =
b

==> 9 - 4*1*b <
0

==> 9- 4b <
0

==> -4b <
-9

==> b >
9/4

Then the values of b should be greater that
9/4

Then, b belongs to the interval ( 9/4 ,
inf )