03 Foundational Differentiation Rules: Power, Product, and Quotient
Calculus represents the mathematical language of dynamic change. The first derivative of a function y = f(x) measures the sensitivity to change of the function value (y) with respect to a change in its argument (x).
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Power Rule: For any real number n, the derivative of xn is n x^(n-1). When coupled with the constant multiple rule: d/dx [c f(x)] = c f'(x).
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Product Rule: When differentiating a product of two functions, students must avoid the tempting fallacy of simply multiplying their derivatives! The rigorous rule requires: d/dx [u(x) v(x)] = u(x) v'(x) + v(x) u'(x). For three functions: d/dx [u v w] = u' v w + u v' w + u v w'.
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Quotient Rule: For rational functions y = u(x) / v(x) where v(x) ≠ 0: d/dx [u/v] = [v(x) u'(x) - u(x) v'(x)] / [v(x)]². The minus sign in the numerator is mandatory, and the denominator is squared without differentiation.