1) x^4-10x^2+9 = 0 x^2=y => y^2-10y+9=0 y=(10+8)/2=9 => x^2=9 => x=3; x=-3; y=(10-8)/2=1 => x^2=1 => x=1; x=-1 2) (x^2-10)^2-3(x^2-10)+4=0 x^2-10=y => y^2-3y+4=0 D=9-16<0 => uravnenie ne imeet reshenij