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.
Suppose you were feeling ill from a bacterial infection. Chances are the doctor would prescribe an antibiotic and in a few days, you would be feeling better. But there are two main categories of bacteria: gram-positive bacteria and gram-negative bacteria. Unfortunately, gram-negative bacteria are harder to kill with antibiotics. To make matters worse, when gram-negative bacteria are destroyed, say by antibiotics or by our immune system, they release toxins into our body called endotoxins. Endotoxins can make us very sick, and in some cases, even cause death. Where Endotoxins Come From