x² - 10x + 25 = 9
x² - 10x +16 = 0 <---- subtracted 9 from each side .....
Since you there are no factors of 16 that add up to -10 do the quadratic formula : -b + √b² - 4ac
-------------------------
2a
-(-10) + √(10)² - 4(1)(16)
10 + √36
10 + 6
10 + 6 = 16
16 / 2 = 8 <--- your first answer
10 - 6 = 4
4 / 2 = 2 <---- your other answer
so your answer is B { 2,8 }
