Answer:
x∈{-7√2, 7√2}
Step-by-step explanation:
[tex]98-x^2=0\\\\-x^2+98=0\\\\a=-1\,,\ \ b=0\,,\ \ c=98\\\\x_1=\dfrac{-0-\sqrt{0^2-4\cdot(-1)\cdot98}}{2\cdot(-1)}=\dfrac{-\sqrt{4\cdot49\cdot2}}{-2}=\dfrac{-2\cdot7\sqrt{2}}{-2}=7\sqrt2\\\\x_2=\dfrac{-0+\sqrt{0^2-4\cdot(-1)\cdot98}}{2\cdot(-1)}=\dfrac{2\cdot7\sqrt{2}}{-2}=-7\sqrt2[/tex]
