x² = 30 - x
x² + x - 30 = 0
a = 1; b = 1; c = - 30
D = b² - 4ac = 1² - 4 * 1 * (-30) = 1 + 120 = 121
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x1 = (-1+11)/2
x1 = 10/2
x1 = 5
x2 = (-1-11)/2
x2 = -12/2
x2 = -6
ответ: x1 = 5, x2 = -6.
