[tex]\underline{a_{n} = a_1\cdot q^{n-1}}[/tex]
1)
[tex]a_1 = 2\\q = 3\\n = 4\\\\a_4 = a_1\cdot q^{3} = 2\cdot3^{3} = 2\cdot27 = \boxed{54}[/tex]
2)
[tex]a_1 = -2\\q = 3\\n = 2\\\\a_2 = a_1\cdot q = -2\cdot3 =\boxed{ -6}[/tex]
3)
[tex]a_1 = 3\\q = -4\\n = 3\\\\a_3 = a_1\cdot q^{2} = 3\cdot(-4)^{2} = 3\cdot16 = \boxed{48}[/tex]
