Решите уравнение:
1)

(3 x - 1) (9 x^{2} + 3 x + 1) - 9 x (3 x^{2} - 4) = 17

;
2)

(x + 4) (x^{2} - 4 x + 16) - x (x - 7) (x + 7) = 15

;
3)

(x + 6) (x^{2} - 6 x + 36) - x (x - 9)^{2} = 4 x (4, 5 x - 13, 5)

reshalka.com

Алгебре 7 класс Мерзляк. Номер №688

(3 x - 1) (9 x^{2} + 3 x + 1) - 9 x (3 x^{2} - 4) = 17

(3 x)^{3} - 1 - 27 x^{3} + 36 x = 17

27 x^{3} - 27 x^{3} + 36 x = 17 + 1

36x = 18

x = \frac{18}{36} = \frac{1}{2}

(x + 4) (x^{2} - 4 x + 16) - x (x - 7) (x + 7) = 15

x^{3} + 4^{3} - x (x^{2} - 7^{2}) = 15

x^{3} + 64 - x (x^{2} - 49) = 15

x^{3} - x^{3} + 49 x = 15 - 64

49x = −49
x = −49 : 49
x = −1

(x + 6) (x^{2} - 6 x + 36) - x (x - 9)^{2} = 4 x (4, 5 x - 13, 5)

x^{3} + 6^{3} - x (x^{2} - 18 x + 81) = 18 x^{2} - 54 x

x^{3} + 216 - x^{3} + 18 x^{2} - 81 x = 18 x^{2} - 54 x

x^{3} - x^{3} + 18 x^{2} - 18 x^{2} + 54 x - 81 x = - 216

−27x = −216
x = −216 : −27
x = 8

ГДЗ Алгебра 7 класс Мерзляк, Полонский, Якир