In this case, we'll have to carry out several steps to find the solution.
Step 01:
Data
x² - 20x + 98 = 0
Step 02:
ax² + bx + c = 0
a = 1
b = -20
c = 98
[tex]x\text{ = }\frac{-b\text{ }\pm\sqrt[]{b^{2}-4ac}}{2a}[/tex]
x1:
[tex]x1\text{ = }\frac{-(-20)+\sqrt[]{(-20)^2-4\cdot1\cdot98}}{2\cdot1}[/tex][tex]x1\text{ = }\frac{20+2\sqrt[]{2}}{2}=10+\sqrt[]{2}[/tex]x2:
[tex]x2=\frac{-(-20)-\sqrt[]{(-20)^2-4\cdot1\cdot98}}{2\cdot1}[/tex][tex]x2\text{ = }\frac{20-2\sqrt[]{2}}{2}=10-\sqrt[]{2}[/tex]The solution is:
[tex]\begin{gathered} x1\text{ = 10 + }\sqrt[]{2} \\ x2\text{ = 10 - }\sqrt[]{2} \end{gathered}[/tex]