[+preamble]
\usepackage[usenames,dvipsnames,pdftex]{xcolor}
\usepackage{tikz,ifthen}
[/preamble]
\coordinate (A) at (0,0);
\coordinate (B) at (-60:12cm);
\coordinate (C) at (240:12cm);
\foreach \density in {20,30,...,160}{%
\draw[fill=MidnightBlue!\density] (A)--(B)--(C)--cycle;
\path
(A) coordinate (X)
-- (B) coordinate[pos=.15](A)
-- (C) coordinate[pos=.15](B)
-- (X) coordinate[pos=.15](C);
}

% Include tikz into local preamble
[+preamble]
\usepackage{tikz}
[/preamble]
\shade[top color=blue,bottom color=gray!50]
(0,0) parabola (1.5,2.25) |- (0,0);
\draw (1.05cm,2pt) node[above]
{$\displaystyle\int_0^{3/2} \!\!x^2\mathrm{d}x$};
\draw[style=help lines] (0,0) grid (3.9,3.9)
[step=0.25cm] (1,2) grid +(1,1);
\draw[->] (-0.2,0) — (4,0) node[right] {$x$};
\draw[->] (0,-0.2) — (0,4) node[above] {$f(x)$};
\foreach \x/\xtext in {1/1, 1.5/1\frac{1}{2}, 2/2, 3/3}
\draw[shift={(\x,0)}] (0pt,2pt) — (0pt,-2pt) node[below] {$\xtext$};
\foreach \y/\ytext in {1/1, 2/2, 2.25/2\frac{1}{4}, 3/3}
\draw[shift={(0,\y)}] (2pt,0pt) — (-2pt,0pt) node[left] {$\ytext$};
\draw (-.5,.25) parabola bend (0,0) (2,4) node[below right] {$x^2$};

![Rendered by QuickLaTeX.com \[ E=mc^2,\frac{a}{b}=\frac{c}{d}=\frac{a+c}{b+d} \]](http://wuling.name/wp-content/ql-cache/quicklatex.com-313226b70bc501d95a86c17efc899842_l3.png)