X2 -11x+18=0 x2 -4x-4=0 2x2-10x=0

x^2 - 11x + 18 = 0 D = b^2 - 4ac = (-11)^2 - 4*1*18 = 121-72 = 49 VD = V49 = 7 x1 = (11+7)/2 = 18/2 = 9 x2 = (11-7)/2 = 4/2 = 2     x^2 - 4x -4 = 0 D = b^2-4ac = 4^2-4*1*(-4) = 16+16 = 32 VD = V32 = V(16*2) = 4V2                4+4V2            x1 = ----------------- = 2+2V2                 2                    4 - 4V2  x2 = ----------------- = 2 - 2V2                   2   2x^2 - 10x = 0 x (2x-10)=0 x = 0    i     2x-10=0                   2x=10                    x = 10:2                     x = 5