How can we write a formula in file md 3?

How can we write a formula in file md?

We can write a formula in file md similar to write in tex. The formula $x^2+1=0$ can be seen clearly in file md, but when we see this post on website it no longer appear like that. To solve this problem, we use the other web. Code: ![equation](https://latex.codecogs.com/svg.latex?equation)

Example

![\Large x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}](https://latex.codecogs.com/svg.latex?x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}) for