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.
1 Systemic lupus erythematosus (SLE) is the most common type. It can be mild or severe, and can affect many parts of the body. 2  Discoid lupus causes a red rash that doesn't go away. 3  Subacute cutaneous lupus causes sores after being out in the sun.  Drug-induced lupus is caused by certain medicines.