# Knowing when the roots of an expression include imaginary values

• July 1st 2009, 11:43 AM
fcabanski
Knowing when the roots of an expression include imaginary values
How does one know that

4x^2 +3x + 2

has imaginary values for x?
• July 1st 2009, 11:45 AM
Plato
$ax^2 +bx+c=0$ has complex (non-real) roots if $b^2-4ac<0$.
• July 1st 2009, 12:29 PM
fcabanski
Thanks!