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a fost răspuns

Sa se gaseasca primul termen si ratia unei progresii geometrice daca
a6=25 si a8=9

Răspuns :

Acalina
a8=a6*q^2
q^2=a8/a6
q^2=9/25
=>q=3/5
    q=-3/5
a6=a1*q^5
a1=a6/q^5
a1=25/q^5 (=> calcule)
=>a1=5^7/3^5
    a1=-5^7/3^5
Icecon2005
a₈=a₆×q²
q²=a₈:a₆
q²=9:25
[tex]q= \sqrt{ \frac{9}{25} }= \frac{3}{5} [/tex]
a₆=a₁×q[tex] ^{5} [/tex]
a₁=a₆:q[tex]^{5} [/tex]
a₁=25:(3/5)⁵

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