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 symptoms can also make lupus look like certain other diseases. For example, like Chantelle, people with lupus may feel weak and fatigued. They may have muscle aches, loss of appetite, swollen glands, and hair loss. Sometimes they have abdominal pain, nausea, diarrhea, and vomiting.