\infty             ∞
\sum               ∑
\int               ∫
\leftarrow         ←
\alpha             α
\subseteq          ⊆

$$ x = 3 $$

\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{wasysym}
\usepackage{tipa}

\le                 ≤                   \pm                 ±
\ge                 ≥                   \mp                 ∓
\neq                ≠                   \times              ×
\approx             ≈                   \div                ÷
\not\approx         ≉                   \cdot               ⋅
\simeq              ≃                   \circ               ∘
\cong               ≅
\equiv              ≡
\not\equiv          ≢
\not<               ≮
\not>               ≯
\not\le             ≰
\not\ge             ≱
\ll                 ≪
\gg                 ≫

\emptyset           ∅                   \aleph              ℵ
\in                 ∈                   \beth               ℶ
\notin              ∉                   \neg                ¬
\ni                 ∋                   \wedge              ∧
\not\ni             ∌                   \vee                ∨
\subset             ⊂                   \veebar             ⊻
\subseteq           ⊆                   \forall             ∀
\not\subset         ⊄                   \exists             ∃
\not\subseteq       ⊈                   \top                ⊤
\subsetneq          ⊊                   \bot                ⊥
\supsetneq          ⊋                   \therefore          ∴
\supset             ⊃                   \vdash              ⊢ 
\supseteq           ⊇                   \models             ⊨ 
\cup                ∪                   \Box                □
\cap                ∩                   
\bigcup             ⋃                   
\bigcap             ⋂                   
\setminus           ∖

\angle              ∠
\triangle           △
\perp               ⊥
\parallel           ∥
\cong               ≅
\sim                ∼

\infty              ∞                   \lfloor             ⌊
\Delta              Δ                   \rfloor             ⌋
\nabla              ∇                   \lceil              ⌈
\partial            ∂                   \rceil              ⌉
\sum                ∑                   \|                  ∥
\prod               ∏                   \langle             ⟨
\int                ∫                   \rangle             ⟩
\iint               ∬                   '                   ′
\iiint              ∭                   ''                  ″
\iiiint             ⨌                  '''                 ‴
\oint               ∮
\Re                 ℜ
\Im                 ℑ
\wp                 ℘

\oplus              ⊕                   \bigoplus           ⨁
\otimes             ⊗                   \bigotimes          ⨂
\triangleleft       ◃
\unlhd              ⊴
\rtimes             ⋊
\wr                 ≀

^0                  ⁰                   _0                  ₀
^1                  ¹                   _1                  ₁
^2                  ²                   _2                  ₂
^3                  ³                   _3                  ₃
^a                  ᵃ                   _a                  ₐ
^b                  ᵇ
^c                  ᶜ
^A                  ᴬ
^B                  ᴮ
^+                  ⁺                   _+                  ₊
^-                  ⁻                   _-                  ₋
^=                  ⁼                   _=                  ₌
^(                  ⁽                   _(                  ₍
^)                  ⁾                   _)                  ₎
^\alpha             ᵅ
^\beta              ᵝ                   _\beta              ᵦ
^\gamma             ᵞ                   _\gamma             ᵧ

\rightarrow         →                   \Rightarrow         ⇒
\leftarrow          ←                   \Leftarrow          ⇐
\uparrow            ↑                   \Uparrow            ⇑
\downarrow          ↓                   \Downarrow          ⇓
\nwarrow            ↖                  \nearrow            ↗
\searrow            ↘                  \swarrow            ↙
\mapsto             ↦
\leftrightarrow     ↔                   \Leftrightarrow     ⇔ 
\rightarrowtail     ↣
\twoheadrightarrow  ↠
\hookrightarrow     ↪

\cdot               ⋅
\cdots              ⋯
\ddots              ⋱
\ldots              …
\vdots              ⋮