solve the inequalities

Ans:



It is a simple quadratic function.
First, draw the graph of f(x).
You will see, b/w 3 & 4, graph will lie below the x-axis.
And the graph of |f(x)| will lie above x-axis b/w 3 & 4.
And over the rest region, graph of f(x) & |f(x)| will overlap.
So, the final solution is