$Ax^2+Bx+C=0$ $\frac{a}{b} = \frac{c}{d} \Leftrightarrow ad = bc$ <script type='text/x-mathjax-config'> MathJax.Hub...

Look back your facebook history

Celebrating its 10th birthday facebook introduced a special feature called  "lookback"  .The feature presents a vedio of your ...