Запись логарифмов: log(основание, число).
log²(2, x) + 3 = 2log(2, x²),
log²(2, x) + 3 = 4log(2, x);
log(2, x) = t,
t² + 3 = 2t,
t² - 4t + 3 = 0,
D = (-4)² - 4*3 = 16 - 12 = 4 = 2²,
t = (4 ± 2)/2 = 2 ± 1,
t1 = 1, t2 = 3;
log(2, x) = 1 и log(2, x) = 3,
x = 2¹ и x = 2³,
x = 2 и x = 8.
Ответ: 2; 8.