Update README.md

Signed-off-by: Fabiana 🚀  Campanari <113218619+FabianaCampanari@users.noreply.github.com>

Author: FabianaCampanari

README.md

@@ -668,6 +668,10 @@ $3x_1 \leq 90
 
 ### $x_1 \geq 0, \quad x_2 \geq 0$
 
+```latex
+x_1 \geq 0, \quad x_2 \geq 0
+```
+