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Iuliamanescu
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[tex] \frac{1}{ \sqrt{5}-2 } + \frac{1}{ \sqrt{5} +2} .aratati ca a ∈ (√19,√21)[/tex]

Răspuns :

Renatemambouko
1/(√5-2) + 1/(√5+2)=
(√5+2+√5-2)/(√5-2)(√5+2)=
2√5/(5-4)=2√5=√20
CarMina03
a=1/√5-2+1/√5+2=(√5+2)/(5-4)+(√5-2)/5-4=√5+2+√5-2=2√5=√2²*5=√20
a=√20∈(√19,√21)

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