Hey mrsmarthi, i went through the link given for quad. eqns. It was of tremendous help.Thanks !!
I am posting my solution to the problem in this post using that method. Can you ( or anyone else perhaps) review it and tell me if it is indeed, the right way to go.
SOLUTION :
Since x+1/x<2.5,
I consider x+1/x-2.5<0 and further, i break it down to x+1/x-2.5 = y and y<0.
Now I solve the quadratic eqn considering y=0 i.e. x+1/x-2.5=0 and get the solution, (x-2)*(x-.5)=0.
Thus, on the number line, I plot the points .5 and 2 on the x -axis. We now have three regions on the x axis, which are
x>2, .5<x<2 and x<.5.
Now, for the main equation, we need to see y<0 lies in which of the three regions.
x+1/x-2.5 =0 can be written as x^2-2.5x+1=0. We can find the vertex of the parabola using the formula, v=(-b/2a,c-b^2/4a).
Which gives us v below the x -axis between .5 and 2 and .5 and 2 are the x-intercepts of the parabola.
Thus, between .5 and 2, the parabola x+1/x-2.5 or simply y is less than zero.