x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}
2 = \left(
\frac{\left(3-x\right) \times 2}{3-x}
\right)
ax^2 + bx + c = 0
S_{\text{new}} = S_{\text{old}} - \frac{ \left( 5-T \right) ^2} {2}
\int_a^x \!\!\!\int_a^s f(y)\,dy\,ds
= \int_a^x f(y)(x-y)\,dy
\sum_{m=1}^\infty\sum_{n=1}^\infty\frac{m^2\,n}
{3^m\left(m\,3^n+n\,3^m\right)}
u'' + p(x)u' + q(x)u=f(x),\quad x>a
|\bar{z}| = |z|,
|(\bar{z})^n| = |z|^n,
\arg(z^n) = n \arg(z)
\lim_{z\rightarrow z_0} f(z)=f(z_0)
\phi_n(\kappa) =
\frac{1}{4\pi^2\kappa^2} \int_0^\infty
\frac{\sin(\kappa R)}{\kappa R}
\frac{\partial}{\partial R}
\left[R^2\frac{\partial D_n(R)}{\partial R}\right]\,dR
\phi_n(\kappa) =
0.033C_n^2\kappa^{-11/3},\quad
\frac{1}{L_0}\ll\kappa\ll\frac{1}{l_0}
f(x) =
\begin{cases}
1 & -1 \le x < 0 \\
\frac{1}{2} & x = 0 \\
1 - x^2 & \mbox{otherwise}
\end{cases}
{}_pF_q(a_1,\dots,a_p;c_1,\dots,c_q;z)
= \sum_{n=0}^\infty
\frac{(a_1)_n\cdots(a_p)_n}{(c_1)_n\cdots(c_q)_n}
\frac{z^n}{n!}
\frac {a}{b}\ \tfrac {a}{b}