если с дискриминантом то

1.

[tex]d = 16 - 20 = \sqrt{ - 4} [/tex]

2.

[tex]d = 9 + 280 = \sqrt{289} = 17[/tex]

[tex]x1x2 = \frac{3 + - 17}{2} = 10 \: and \: - 7[/tex]

[tex]d = 36 + 664 = \sqrt{700} = 10 \sqrt{7} [/tex]

[tex]x1x2 = \frac{6 + - 10 \sqrt{7} }{2} [/tex]