diff --git a/TeX-support.md b/TeX-support.md
index 503ca1b..345b399 100644
--- a/TeX-support.md
+++ b/TeX-support.md
@@ -1 +1,8 @@
-Now writing...
\ No newline at end of file
+You can write math by TeX. With $$ and $$$, write some equations.
+
+```
+# TeX support
+$$$ 1 + \frac{q^2}{(1-q)}+\frac{q^6}{(1-q)(1-q^2)}+\cdots = \prod_{j=0}^{\infty}\frac{1}{(1-q^{5j+2})(1-q^{5j+3})}, \quad\quad \text{for }\lvert q\rvert<1. $$$
+```
+
+![image](https://user-images.githubusercontent.com/11307908/31156444-5753ad3a-a8ef-11e7-98aa-7b5cbe3a3403.png)