Fie b1≠0 si q≠0;
b2=b1*q⇔b2=b1*q=6(1)
b5=b1*[tex] q^{4} [/tex] =48 (2)
(2):(1)⇒[tex] \frac{48}6} [/tex] =[tex] \frac{b5}{b2} [/tex] =[tex] \frac{b1* q^{4} }{b1*q} [/tex]
Simplifici b1 => [tex] \frac{ q^{4} }{q} [/tex] =[tex] \frac{48}{6} [/tex]=<=> [tex] q^{3} [/tex] =8<=> [tex]q^{3} [/tex] =[tex]2^{3} [/tex] <=> q=2
Din rel (1)=>b1=[tex] \frac{6}{q} [/tex] =6/2=3
b7=b1*[tex]q^{6} [/tex] =3*64=192
Sn=b1+b2+...+bn= b1*([tex] \frac{ q^{n}-1 }{q-1} [/tex]) =3*[tex] \frac{ (2^{n}-1) }{2-1} [/tex] =3*(2^n-1)
