#text "Einstein wrote $E = mc^2$ inline."

#text "$$\n\\frac{\\partial \\mathbf{u}}{\\partial t} + (\\mathbf{u} \\cdot \\nabla)\\mathbf{u} = -\\frac{1}{\\rho}\\nabla p\n$$"

#text "Backslash inline (\\frac{1}{5}) and display:"

#text "[\\frac{\\pi}{4} < \\theta < \\frac{\\pi}{2}]"