Hello,
you asked this question already. I couldn't get a simple solution and I can only show you how to get some approximations:
1. you only can factor the LHS of this inequality:
but I don't know how to use this "result".
2. What I did:
Consider the function:
Calculate the zeros of f by the Newton method. I got:
Using these values to 2 sign. digits you can factor the term f(x) into:
Now calculate
A product of 3 factors is negative (that's the same as lower zero) if 2 factors have the same sign and one factor is negative. Thus you'll get a system of linear inequalities:
Now solve these inequalities for x. The final result should be:
I've attached diagrams of the graph of and . Those parts of the graph which are below y = 22 are marked in green or red.