1) x^4 - 5x^5 +4 = 0
x^2(x^2 - 5x)= - 4
x^2 - 5 + 4 = 0
x =0; x^2 = - 4, x^2 - 5 = - 4; x = - 1, 1
2) x^4 + 8x^2 - 9 = 0
x^2( x^2 - 8x)= 9
x^2=-9; x^2 - 8=-9; x^2 = - 1
3) думать надо
1) x^4 - 5x^5 +4 = 0
x^2(x^2 - 5x)= - 4
x^2 - 5 + 4 = 0
x =0; x^2 = - 4, x^2 - 5 = - 4; x = - 1, 1
2) x^4 + 8x^2 - 9 = 0
x^2( x^2 - 8x)= 9
x^2=-9; x^2 - 8=-9; x^2 = - 1
3) думать надо