a_1=729
a_n=96
S_n=1995
a_n=a_1*q^{n-1}
S_n=a_1*\frac{1-q^n}{1-q}
\left \{ {{729*q^{n-1}=96} \atop {729*\frac{1-q^n}{1-q}=1995}} \right.
\frac{q^n}{q}= \frac{96}{729} =\frac{32}{243}
729-729q^n=1995-1995q
1995q-729q^n=1266|/q
1995-729*\frac{q^n}{q}=\frac{1266}{q}
1995-729*\frac{96}{729}=\frac{1266}{q}
1995-96=\frac{1266}{q}
1899=\frac{1266}{q}
q=\frac{1266}{1899}=\frac{2}{3}| > Odpowiedź
\frac{(\frac{2}{3})^n} {\frac{2}{3} }=\frac{32}{243}
(\frac{2}{3})^n=\frac{32}{243}*\frac{2}{3}
(\frac{2}{3})^n=\frac{64}{729}
(\frac{2}{3})^n=(\frac{2}{3})^6
n=6| > Odpowiedź