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.
The three main types of lupus are: 1  Systemic lupus erythematosus, or SLE, which can affect multiple organs in the body and is the most common form of the disease.  Cutaneous (or skin) lupus, which usually affects only the skin and is characterized by a rash on the scalp, legs, or arms.