Question 1075732
.
<pre>
Let
f(x)={&#8722;6x^2+2x  for x<0,
f(x)={3x^2-2     for x&#10878;0.

According to the definition of the derivative, to compute f&#8242;(0), we need to compute the left-hand limit 

limx&#8594;0&#8722; =?

 , which is 
undefined                   <<<---+++ W R O N G
 , 

and the right-hand limit 

limx&#8594;0+?

 , which is 
0                           <<<---+++ C O R R E C T
 . 

We conclude that f&#8242;(0) is 
undefined
 . 
</pre>