[tex]a_4 =2\\a_8 = 162\\q= ?\\a_1 = ?[/tex]
[tex]a_{n} = a_1\cdot q^{n-1}\\\\a_4 = a_1\cdot q^{3} = 2\\\\a_8 = a_1\cdot q^{7} = 162\\\\a_1\cdot q^{7} = 162\\a_1\cdot q^{3} = 2\\------- \ \ \ (dzielimy \ stronami)\\\\\frac{q^{7}}{q^{3}} = \frac{162}{2}\\\\q^{4} = 81\\\\q^{4} = 3^{4}\\\\\boxed{q = 3}[/tex]
[tex]a_1\cdot q^{3}=2\\\\a_1\cdot3^{3} = 2\\\\a_1\cdot27 = 2 \ \ \ |:27\\\\\boxed{a_1 = \frac{2}{27}}[/tex]
