X^{2}- 6x+8=0 x^{2}-5x+6=0
X^2 - 6X + 8 = 0 D = 36 - 32 = 4 ; √ D = 2 X1 = ( 6 + 2 ) : 2 = 4 X2 = ( 6 - 2 ) : 2 = 2 ------------------------------ X^2 - 5X + 6 = 0 D = 25 - 24 = 1 ; √ D = 1 X1 = ( 5 + 1 ) : 2 = 3 X2 = ( 5 - 1 ) : 2 = 2