Product Rule. If the two functions f(x) and g(x) are differentiable (i.e. the derivative exist) then the product is differentiable and, The proof of the Product Rule is shown in the Proof of Various Derivative Formulas section of the Extras chapter.
Inflammation is the most common reason for muscle pain and aches. Any time that major inflammation exists (strep throat, hepatitis, cancer, lupus, acute heart attack, etc.), signs and symptoms often include fevers, sweats, chills, fatigue, weight loss, and various muscle aches, pains and weakness.
Symptoms of Lupus. Although most people with Lupus experience symptoms in a few organs only, Lupus can affect any part of the body. Ninety-five percent of people with Lupus experience achy joints, or, 'Arthralgia.' Ninety-percent experience fevers of more than one-hundred degrees, and arthritis or swollen joints.