Question

How can you tell if a function has no real roots? For example:x^4+13x^2+36=0

Answer 1

discriminant

Answer 2

discriminant = sqrt(b^2 - 2ac).
if its 0, 1 real root,
if >0, 2 real roots,
<0, only complex roots

Answer 3

but if you graph it, there are no real roots

Answer 4

:S

Answer 5

this is weird :/

Answer 6

wait actually if you substitue x^2 by a, u get x^2+4 and x^2+9, and those don't have real roots

Answer 7

so thats why the equation has no real roots

Answer 8

:D