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.
What makes it worse is, the more you try not to think, the more your mind has to reference it to not think of it. An example: Don't think of your car. Stop thinking of your car! I don't want you to think of your car!....And there it is.