The points are .
Luisa is correct, because substitute the values of in the slope formula .
.
Luisa is correct.
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in the slope formula ![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=53f79335407a3d7a0ac01b4fe461c488.png\")
.![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=0419c3a1d5186b6efab18e69f77dc0e2.png\")
.![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/solution.JPG\")