2x-6/4-4x+x的平方/(x+3)*x的平方+6x+9/3-x
=2﹙x-3﹚÷﹙x-2﹚²÷[﹙x+3﹚×﹙x+3﹚²]÷﹙3-x﹚
=2﹙x-3﹚×1/﹙x-2﹚²×1/﹙x+3﹚³×1/﹙3-x﹚
=﹣2／[﹙x-2﹚²×﹙x+3﹚³]