1)
[tex]y = \frac{x - 4}{x^2 - 9}[/tex]

2)
[tex]y ={x}^{2} + 4x + 1[/tex]

3)
[tex]y = \sqrt{ {x}^{2} + 4x} [/tex]

4)
[tex]y = \frac{x}{ \sqrt{x - 4} } [/tex]
​