√x = 3
x = 3²
x = 9
x² = 3
x = √3
x = - √3
x² = - 3
x² + 3 = 0
D = b² - 4ac = 0² - 4 × 1 × 3 = 0 - 12 = - 12 - дискрименант отрицательный,значит,корней нет.
x² - 2,25 = 0
D = b² - 4ac = 0² - 4 × 1 × (- 2,25) = 9 = 3²
x1 = 3 / 2 = 1целая 1/2
x2 = - 3/2 = - 1целая 1/2