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IAlex
a fost răspuns

E(x)= (1/x +1/x la a doua + 1/x la a treia) : 1 + x + x la a doua/x la a patra - x la a treia. Demonstrati ca E(x)= x-1

Răspuns :

E(x)=[(1/x+1/x²+1/x³):(1+x+x²)/(x⁴-x³)]
E(x)=[(x²+x+1)/x]·[(x⁴-x³)/(1+x+x²)]
E(x)=[(1+x+x²)/x]·[x(x-1)/(x+x+x²)] simplificam cu x si 1+x+x²
E(x)=x-1

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