EDIT: Let this be a warning to anyone relying on a calculator. I should have trusted myself. I entered the range in the opposite way to the calculator giving a negative solution.
Have a homework question here:
I can get out:
but this equals for me positive 2.8... When looking at the graph (and the solve on the calc) shouldn't it be negative? Where have I gone astray? (I think the second part of that is 0 so I assume I am doing somethign wrong in the first part).