5.3 The Fundamental Theorem of Calculus/10

Failed to parse (unknown function "\cdotF"): {\displaystyle \begin{align} g(r)=\int_{0}^{r}\sqrt{x^2+4}dx \\[2ex] \frac{d}{dx}\int_{0}^{r}\sqrt{x^2+4}dx \\[2ex] \frac{d}{dx}\int_{b(x)}^{a(x)}F(t)dt=\frac{d}{dx}[b(x)]\cdotF(b(x))\\[2ex] 1\cdot\sqrt{r^2+4} - 0\cdot\sqrt{0^2+4} \\[2ex] =\sqrt{r^2 + 4} \end{align} }