Since there is an absolute value ∣x+9∣, split into two cases based on the sign of (x+9).
When x≥−9, ∣x+9∣=x+9:
x2−(x+9)+x>0
x2−x−9+x>0
x2−9>0
(x−3)(x+3)>0
This is positive when x<−3 or x>3.
Applying the restriction x≥−9, the solution from this case is [−9,−3)∪(3,∞).
When x<−9, ∣x+9∣=−(x+9):
x2+(x+9)+x>0
x2+2x+9>0
(x+1)2+8>0
Since (x+1)2≥0, this expression is always ≥8>0, so the inequality holds for all x<−9.
The solution from this case is (−∞,−9).
Combining both cases:
(−∞,−9)∪[−9,−3)∪(3,∞)
=(−∞,−3)∪(3,∞)