Question 388277
x^3+5x^2-9x-45=x^2(x+5) -9(x+5) by grouping
 
we have (x+5)(x^2-9) is the function.
 
Since the roots are simple, and that for x->-oo the function goes to negative values, we have : 
 
the domain where the function is positive is : [-5;-3]U[3,+oo[

*[invoke plot_any_inequality "x^3+5x^2-9x-45>0", -10, 10, -10, 10, 300, 300]