Question

sum of arithmetic sequence 6+10+14...

Answer 1

what is
a=?
d=?
n=?

Answer 2

I dont really know.All I have is 6+10+14...+86

Answer 3

see a is the first term

so here a=6
d is the difference between each consecutive terms
here d=10-6 =4 ( it is either 10-6=4,14-10=4 ... it is constant for arithmetic sequence)
n is the number of term
her 86 is the nth term so we need to find n first
using
nthterm= firstterm +(n-1)*(common difference)
i.e
86=6+(n-1)*4
80=(n-1)*4
hence n-1=80/4
n-1=20

to find 6+10+14...+86
we have a=6 d=4 n=21 and the last term=86
thus reqd Sum= (n/2)*(firstterm+lastterm)=21/2 *(6+86)=21/2*92=21*46=966
n=20+1
n=21

Answer 4

@matricked please donot provide direct worked out solutions like that its against openstudy COC .Instead help the user get to the answer .

Answer 5

@deeva123 If you're asking a question that involves finding the sum of an arithmetic sequence, you must be learning the topic Series and Sequences. If you're unsure of a question, you must reflect on your notes given or provided by your teacher or notes from your maths textbook. Whatever gives you information about sum of Arithmetic Sequences, will help you.