hello, can you help me to solve this question?

Question

x^2+9>0
thank you''

Answer 1

(x+3)(x-3)>0

which means x cannot be 3, or -3

Then test to see if the inequality is good for -inf<x<-3, from -3<x<3, and from 3<x<inf

Answer 2

bobpursley,

How can you factor x^2 + 9 into
(x - 3) (x + 3) when there is a PLUS sign between x^2 and the constant 9?

Get my point?