Answer:
C [tex]11+13+15+17+...[/tex]
Step-by-step explanation:
Consider the series
[tex]\sum\limits_{n=3}^{\infty}(2n+5)[/tex]
The nth term of series is [tex]a_n=2n+5[/tex]
The bottom index tells you that n starts changing from 3, so
[tex]a_3=2\cdor 3+5=11\\ \\a_4=2\cdot 4+5=13\\ \\a_5=2\cdot 5+5=15\\ \\a_6=2\cdot 6+5=17\\ \\...[/tex]
Thus, the sum of all terms is
[tex]11+13+15+17+...[/tex]
