Question

Calcular a soma dos 50 primeiros termos da P.A. (8, 14, 20...)

Answer 1

$an=a1+(n-1)r\\ an=8+(50-1)6\\ an=8+(49)*(6)\\ an=8+294\\ an=302\\ \\ Sn=(\frac { a1+an }{ 2 } )n\\ \\ Sn=(\frac { 8+302 }{ 2 } )50\\ \\ Sn=(8+302)25\\ Sn=310*25\\ Sn=7750$