bagaimana cara menghitung 5 + 6 + 7 + 8 +....+ 80 =

a = 5
b (Selisihnya) = 1
Un = 80
a+(n-1)b = 80
5+(n-1)1 = 80
n-1 = 75
n = 76

[tex]S_n=\frac{n}{2}(a+U_n) \\ S_{76}=\frac{76}{2}(a+U_{76}) \\ S_{76}=38(5+80)=38\times 85=3.230[/tex]