Question

9 класс
(x^2+6x)^2+2(x+3)^2=81

Answer 1

(x^2 + 6x)^2 + 2(x^2 + 6x + 9) - 81 = 0
x^2 + 6x = a,
x^2 +6x + 9 = a + 9,
a^2 + 2(a + 9) - 81 = 0,
a^2 + 2a - 63 = 0
а1 = -9
a2 = 7

x^2 + 6x = -9
x^2 + 6x + 9 = 0
x = -3

x^2 + 6x = 7
x^2 + 6x -7 = 0
x1 = -7
x2 = 1

ответ. -7; -3; 1.

Answer 2

и да спасибо