Formula termenului general a unei progresii geometrice:
[tex]b_n=b_1\cdot q^{n-1}[/tex]
Unde q este ratia.
[tex]b_4=b_1\cdot q^3=10\\
4\cdot q^3=10\\
q= \sqrt[3]{\frac{5}{2}} [/tex]
[tex]b_{25}=b_1\cdot q^{24}=4\cdot (\sqrt[3]{\frac{5}{2}})^{24}=4\cdot (\frac{5}{2})^8= \frac{5^8}{2^6} [/tex]