Question

$1) x^{4}-34 x^{2} +225=0 2) x^{4}- 20 x^{2} +64=0$

Answer 1

$x^{4}-34x^{2}+225=0\ x^{2}=t\ t^{2}-34t+225=0\ t_{1}=25\ t_{2}=9\ x^{2}=25\ x=5;x=-5;\ x^{2}=9\ x=3;x=-3;$

Ответ: -3, 3, -5, 5.

$x^{4}-20x^{2}+64=0\ x^{2}=t\ t^{2}-20t+64=0\ t_{1}=16\ t_{2}=4\ x^{2}=16\ x=4;x=-4;\ x^{2}=4\ x=2;x=-2;$

Ответ: -2, 2, -4, 4.