[br]Use CAS to simplify:[br][br][b]Simplify[(x^2 - 9)/(x - 3)][/b][br][br][br][br]Then try:[br][br][b]Simplify[(x^2 - 4x + 4)/(x - 2)][/b]
[b]What happens? What assumptions is CAS making? When is the simplified form [i]not[/i] valid?[/b]
[br][br]Use:[br][br][b]Factor[x^2 - 9][br][br]Factor[x^2 - 4x + 4][/b][br][br][br]Then:[br][b](x^2 - 4x + 4)/(x - 2)[/b]
[b]Why is factoring useful before simplifying?[/b][br][b]Could students reach incorrect conclusions if they skip domain analysis?[/b]