contestada

Work out the sum of the first 60 terms of the following arithmetic series:
100 + 94 + 88 +...

Respuesta :

Answer:

[tex]S_{60}=-4620[/tex]

Step-by-step explanation:

[tex]S_n=\frac{n}{2}[2a_1+(n-1)d]\\ \\S_{60}=\frac{60}{2}[2(100)+(60-1)(-6)] \\\\S_{60}=30[200+(59)(-6)]\\ \\S_{60}=30[200-354]\\ \\S_{60}=30[-154]\\\\S_{60}=-4620[/tex]