# How to write down the equations? [duplicate]

I am new at the website. I see that there are equations in many posts as well as in the answers. I can't write down this equation in this website. But I need to write it.

This may seems to off-topic. Can anyone help me writing the equations in a question or in the answers in the website?

## marked as duplicate by user642796Sep 12 '14 at 17:19

Here's an example of an equation $$ax^2+bx+c=0$$ To type this, I entered "\$\$ ax^2+bx+c=0 \$\$", without the quotes.