Assuming that x1 is the x you mention later, the differential equation is

Since
, the equation becomes

i.e., the derivative is constant. If the derivative is constant, the original function is a line with slope that constant, i.e. the solution of the differential equation is

So, if
, the line grows when x grows, and so the more you listen, the more bored you are.
If otherwise
, the line descends when x grows, and so the more you listen, the less bored you are.
Finally, if also
, then the derivative is constantly zero, which means that the original function is a constant. So, your level of boredom is always the same, no matter how many hours of tutorials you listen to.