Question

(x−1)(x 2 +x+1)−x(x 2 −1)=7;

Answer 1

$(x - 1)( {x}^{2} + x + 1) - x( {x}^{2} - 1) = 7 \\ {x}^{3} + {x}^{2} + x - {x}^{2} - x - 1 - {x}^{3} + x = 7 \\ x - 1 = 7 \\ x = 8$

Ответ: 8