a)
4x³ +3x² =x² ;
4x³ +3x² - x² =0 ;
4x³ +2x²= o ;
4x²(x +1/2) =0 ;
x₁ =0 ;
x₂ = -1/2 .
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б)
u ³ +u =2u ;
u ³ +u - 2u =0 ;
u ³ - u =0 ;
u(u² -1) =0 ;
(u+1)u(u -1) =0 ;
u₁ = -1;
u₂ = 0 ;
u₃ =1.
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в)
5y³ +5y =0 ;
5y(y² +1) =0 ;
y =0 . ( y² +1 ≥ 1 ≠0)
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г)
7t⁴ +14t² = 0
7t²(t² +2) = 0 ;
t =0 . t² +2 ≥2 ≠0