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Rezolvati in IR ecuatia bipatrata: [tex] x^{4} +11 x^{2} +18=0[/tex]

Răspuns :

x e R  

daca x < 0 => x^2 > 0 si x^4 >0 => x^4 +11*x^2 >0
=> x^4 +11*x^2 +18>18
daca x>0 => acelasi lucru ca la x<0
daca x=0 =>  0+0+18 =18

=> x^4 +11*x^2 +18 =0 nu are solutii in R