X^3+9x^2-108¡Ý0

Answer 1

If you mean to solve
x^3+9x^2-108 <= 0
first find the factors:
(x+6)^2 (x-3) <= 0

Now, (x+6)^2 >= 0 for all x, so we want
(x-3) <= 0
x <= 3

Makes sense, since if you think of the graph, it comes up from lower left, touches the x-axis at x = -6, dips back down, and finally crosses into positive values at x=3.