x²+px+q=0

x1+x2=-p

x1*x2=q

1)

-p=-14+6=-8

p=8

q=-14*6=-84

x²+8x-84=0

2)

-p=-1/6-2/3

p=5/6

q=(-1/6)*(-2/3)=2/18=1/9

x²+(5/6)x+1/9=0

3)

[tex] - p = (7 - 5 \sqrt{2} ) + (5 \sqrt{2} + 7) = 14 \\ p = - 14 \\ q = (7 - 5 \sqrt{2})(7 + 5 \sqrt{2} ) = 49 - 50 = - 1 \\ x^{2} - 14x - 1 = 0[/tex]