TeX source:

\left\{\begin{array}{l} \text { area bounded between the graph } \\ \text { of } \mathrm{f} \text { and the } x \text {-axis and } \\ \text { vertical lines at } x=\mathrm{a} \text { and } x=\mathrm{b} \end{array}\right\} = \int_{\mathrm{a}}^{\mathbf{b}} \mathrm{f}(x) \mathrm{dx}=\mathbf{F}(\mathrm{b})-\mathrm{F}(\mathrm{a})