Question

x в кубе -8x = 7 найдите x

Answer 1

Ответ на картинке внизу страницы

Answer 2

${x}^{3} - 8x = 7 \ {x}^{3} - 8x - 7 = 0 \ (x + 1)( {x}^{2} - x - 7) = 0 \ x + 1 = 0 \ x1 = - 1 \ - - - - - - \ {x}^{2} - x - 7 = 0 \ d = 1 - 4 times ( - 7) = 1 + 28 = 29 \ x2 = frac{1 + sqrt{29} }{2} \ x3 = frac{1 - sqrt{29} }{2}$