Observe the figure:
Kimi is correct,Since could be negative, but is always positive, so does not need to be kept within the absolute value symbol.
Therefore, Kimi is correct.
Kimi is correct.
![\"\"](\"/userfiles/image/steps_images/step1.JPG\")
![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=8da2268e35b6b6daab9c47f71c4c8bf4.png\")
could be negative, but ![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=5b24292c45e7ac7844fdfc7a76bbb58a.png\")
is always positive, so ![\"\"](\"http://www.mathskey.com/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=5b24292c45e7ac7844fdfc7a76bbb58a.png\")
does not need to be kept within the absolute value symbol.![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/solution.JPG\")