Find the derivative of y = [A(x)]^{α}[B(x)]^{β}[C(x)]^{γ} , where α, β, \text{and} γ are constants and A, B, and C are positive functions.
First, take the natural logarithm of each side to obtain
\ln y=\alpha\ln(A(x))+\beta\ln(B(x))+\gamma\ln(C(x))Differentiation w.r.t. x yields
{\frac{y^{\prime}}{y}}=\alpha{\frac{A^{\prime}(x)}{A(x)}}+\beta{\frac{B^{\prime}(x)}{B(x)}}+\gamma{\frac{C^{\prime}(x)}{C(x)}}Multiplying by y, we have
y^{\prime}=\left[\alpha\frac{A^{\prime}(x)}{A(x)}+\beta\frac{B^{\prime}(x)}{B(x)}+\gamma\frac{C^{\prime}(x)}{C(x)}\right][A(x)]^{\alpha}[B(x)]^{\beta}[C(x)]^{\gamma}