Find the sum of the terms of the arithmetic sequence. 1, 7, 13, 19, . . ., 109 n = 19

A. 2204

B. 2090

C. 1045

D. 1102

Question

Find the sum of the terms of the arithmetic sequence. 1, 7, 13, 19, . . ., 109 n = 19

A. 2204	

B. 2090	

C. 1045	

D. 1102

hartnn · Answer

can u find the common difference of your sequence >?

hartnn · Answer

know what common difference is ?

anonymous · Answer

nope lol

hartnn · Answer

its the difference between current term and previous term.
so what is 
13-7 = ? 
7-1 = ?

anonymous · Answer

13- 7 =6?
7-1=6?

hartnn · Answer

yes! so common difference  d= 6 . now what remains is just using the formula
$\huge S_n=(n/2)(2a+(n-1)d)$ 
where d= 6, n= 19 is given  and a =1st term =1
can u calcilate sum now ?

anonymous · Answer

im still confused

hartnn · Answer

confused on what? substituting the values in formula ?