\
The expression is
.
\
Apply product of a sum and a difference formula:
.
\
\
.
\
\
The value of
.
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.![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=51a3819c48c593a0a77e70a9a07daf61.png\")
.![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=cddf3958f7257996f55bd9dda7af8dfe.png\")
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.![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/solution.JPG\")
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.