Respuesta :

you're just adding 5 
example
8+5= 13
13+5=18
18+5=23
23+5=28
28+5=33
and so on :)

Answer: a+6d will defines the series for seven terms i.e. 38.

Step-by-step explanation:

Since we have given that

[tex]8+13+18+......[/tex]

Here, a = first term = 8

d = common difference is given by

[tex]a_2-a_1\\\\=13-8\\\\=5[/tex]

So, we need to find the seven terms:

So, here n = 7

So, it becomes,

[tex]a_7=a+(n-1)d\\\\a_7=8+(7-1)5\\\\a_7=8+6\times 5\\\\a_7=8+30\\\\a_7=38[/tex]

Hence, a+6d will defines the series for seven terms i.e. 38.