$$1+1=2$$
$$2>1$$
$$\gt \geqq = \ne \leqq \lt \fallingdotseq \risingdotseq $$
$$\pm1 \mp1$$
$$\infty$$
$$2\cdot3^4$$
$$2\cdot3^{n-1}$$
$${1 \over 2}*2=1$$
$$\frac{1+2}{2}*2=3$$
$$\sqrt{2^2} = 2$$
$$\sqrt[3]8 = 2$$
$$\log_2 8 = 3$$
$$\therefore y=x+1$$
$$\mathbf{sin}2{\theta}=2\mathbf{sin}{\theta}\,\mathbf{cos}{\theta}$$
$$\sin^{2} \theta + \cos^{2} \theta = 1$$
$$\mathbf{sin}(\alpha+\beta)=\mathbf{sin}{\alpha}\,\mathbf{cos}{\beta}+\mathbf{cos}{\alpha}\,\mathbf{sin}{\beta}$$
$$a_n=a+(n-1)d$$
$$s_n=\frac{1}{2}n(a_1+a_n)=\frac{1}{2}n \{ 2a+(n-1)d \}$$
$$\sum_{k=1}^n k^2 = 1^2+2^2+3^3+\dots+n^2=\frac{n(n+1)(2n+1)}{6}$$
$$\sum_{n=1}^\infty ar^{n-1}=a+ar+ar^2+\dots =
\begin{eqnarray}
\left\{
\begin{array}{l}
\dfrac{a}{1-r}&(|r|\lt1)\\
発散&(|r|\geqq1)
\end{array}
\right.
\end{eqnarray}
(a\ne0)$$
$$
\begin{eqnarray} \sqrt4 &=& \sqrt{2 * 2} \\
&=& \sqrt{2^2} \\
&=& (\sqrt2)^2 \\
&=& \sqrt2 * \sqrt2 \\
&=& 2
\end{eqnarray}
$$
$$
\begin{pmatrix}
a & b\cr
c & d
\end{pmatrix}
\begin{pmatrix}
1 & 0\cr
0 & 1
\end{pmatrix} =
\begin{pmatrix}
a & b\cr
c & d
\end{pmatrix}
$$
$$f'(x)=\lim_{h\to 0}\frac{f(x+h)-f(x)}{h}$$
$$f'(x) = \lim_{ \Delta x \to 0 } \frac{ f(x + \Delta x) - f(x) }{ \Delta x }$$
$$\int_a^b f(x)dx=
\left[ F(x) \right]_{a}^{b}=F(b)-F(a)
$$
$$e^{i\pi} = -1$$