x 2 sum - The total of each value in the x column squared and then added together. y 2 sum - The total of each value in the y column squared and then added together. N - The total number of elements (or trials in your experiment).
Patients with tuberculosis of the lungs have a prolonged illness with fever, cough, night-sweats, weight loss and may occasionally cough up blood. As the disease progresses, symptoms get worse and shortness of breath ensues. Untreated disease can be fatal.
My neighbor stpauler has the right of it. If it developed into a big, nasty infection it can take a while before you get better. In fact, if the infection was bad, you will probably actually feel worse for 1 or 2 days after you take the antibiotics.