ax² + bx + c = 0
D = b² - 4ac
x12 = (-b +- √D)/2a
x² + 7x - 60 = 0
D = b² - 4ac = 49 + 240 = 289
x12 = (-7+-17)/2 = 5 и - 12
m² + m - 90=0
D = 1 + 360 = 361
m12=(-1 +- 19)/2 = -10 и 9
3x² + 32x + 80 = 0
D = 32² - 4*3*80 = 1024 - 960 = 64
x12 = (-32 +- 8)/6 = -4 и -20/3
3x² - 6x + 3 = 0
x² - 2x + 1 =0
(x-1)² = 0
x = 1
