X^2 - 5x + 6,25 - 49 = 0
D = 25 + 171 = 196
x1 = 5 + 14/2 = 9,5
x2 = 5 -14/2 = -4,5
x^2 - 12x + 36 - 121 = 0
D = 144+340 = 484
x1 = 12 + 22/2 = 17
x2 = 12 - 22/2 = -5
9 - 12x + 4x^2 - 0,04 = 0
D = 144 - 143,36 = 0,64
x1 = 12 + 0,8/8 = 1,6
x2 = 12 - 0,8/8 = 1,4
25x^2 + 10x + 1 - 400 = 0
D = 4 + 396 = 400
x1 = -2 + 20/10 = 1,8
x2 = -2 - 20/10 = -2,2