х²-5х+6=0
Решить через дискриминант

-х² + 5х - 6 = 0

х² - 5х + 6 = 0

D = (-5)² - 4 * 1 * 6 = 25 - 24 = 1 > 0  

x₁ = (5 - √1) / (2 * 1) = 4/2 = 2

x₂ = (5 + √1) / (2 * 1) = 6/2 = 3