The function is and .
Alternative form of derivatives : .
.
The derivative of the function at does not exist.
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and ![\"\"](\"http://www.mathskey.com/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=c014272cd268267b82cb2f237c16f854.png\")
.![\"\"](\"http://www.mathskey.com/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=93cbc4c5da7e2ff4b1eca081320db6d6.png\")
.![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=cef9c6fc17fe87eb88869b77d10f39d9.png\")
![\"\"](\"http://www.mathskey.com/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=b739abbe8a16649957255901a3e88b27.png\")
.![\"\"](\"http://www.mathskey.com/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=56a63596b6a8b1caeadd05d8a6a942e6.png\")
does not exist.![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/solution.JPG\")
does not exist.