Question

Решите уровнение
х^4 + х^2 - 20 = 0

Answer 1

$x^4 + x^2 - 20 = 0\\x^2=t\\t^2+t-20=0\\t_1=-5\\t=4\\\\x^2=-5\\x\notin R\\\\x^2=4\\x_1=-2\\x_2=2$