[9, ∞)
|4x+9|≤ 5x
|4x+6|=|2x+8|
(-3 - √5 , -3 + √5 )
x^2 + 6x +4 < 0
x^2 - 3x -18 ≥ 0
{-7/3 , 1}
(-∞ , -3 ] U [ 6 , ∞ )
