Step-by-step explanation:
Given the explicit formula : an = [tex]3^{n-1}[/tex] find the first three terms
n = 1 => a(1) = [tex]3^{1-1}[/tex] = [tex]3^{0} = 1[/tex]
n = 2 => a(2) = [tex]3^{2-1}=3^{1} =3[/tex]
n= 3 => a(3) = [tex]3^{3-1}=3^{2} =9[/tex]
[tex]\left \{ {{a(1)=1} \atop {a(n)=3^{n-1} }} \right.[/tex]
Hope it will find you well.