9x²+bx+2=0
D=b²-4*9*2=b²-72
x₁=(-b-√(b²-72))/18
x₂=(-b+√(b²-72))/18
Либо
x₂/x₁=(-b+√(b²-72))/(-b-√(b²-72))=2
-b+√(b²-72)=2(-b-√(b²-72)
-b+√(b²-72)=-2b-2√(b²-72)
b=-3√(b²-72)
b²=9(b²-72)
b²=9b²-9*72
8b²=9*72
b²=9*9
b=+-9
Либо
x₁/x₂=(-b-√(b²-72))/(-b+√(b²-72))=2
-b-√(b²-72)=2(-b+√(b²-72))
-b-√(b²-72)=-2b+2√(b²-72)
b=3√(b²-72)
b=+-9
Ответ: А)