how to insert fraction & integration in emacs .org file

eg. test.org

\frac{1}{2}
\sqrt{x^2-1}

when I export it into html using org-export-as-html it gives

test.html

\frac{1}{2}
\sqrt{x2-1}

I am new to org-mode.
can anyone tell me whether I am inserted equation in right way??






Thanks & Regards,
Supriya Pravin Sawant