Answer:
6:
[tex] {x}^{2} - 2x - 3 \\ = (x - 3)(x + 1) \\ when \: y = 2 \\ x = 1 \\ vertex \: is \: (1, \: 2)[/tex]
7:
[tex] {x}^{2} = - 625 \\ x = \sqrt{ - 625} \\ x = \sqrt{625} \times \sqrt{ - 1} \\ x = 25 \times \sqrt{ {i}^{2} } \\ x = 25 \times i \\ x = 25i[/tex]
