Let us find the roots of the equation by hit and trial method
x^3 - x^2 -5x -3
put x = 0, 1, -1
at x = 0
=> 0 - 0 - 0 - 3 is not equal to 0
at x = 1
=> 1 - 1 - 5 - 3 is not equal to 0
at x = -1
=> -1 - 1 + 5 - 3 = 0
=> x = -1 is the root of equation
For other roots
put x^2 - 2x - 3 = 0
=> x^2 - 3x + x - 3 = 0
=> x(x - 3) + (x - 3) = 0
=> x= -1 , 3
Given inequality reduced as
(x - 1)(x + 1)(x - 3) > 0
=> x - 1 > 0 or (x + 1) > 0 or (x - 3) > 0
(By Zero product property)
=> x > 0 or x > -1 or x > 3
2) f(x) = (x + 3) / (x - 4) < 0
Multiply each side by (x - 4)
(x - 4) * (x + 3) / (x - 4) < 0* (x - 4)
x + 3 < 0
or x < -3