Question

find the arithmetic series sequence f the fifth term is 19 and S4= a5+1
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Answer 1

Answer:

Let a and d be the first term and common difference of AP respectively.

Now,

a

5

=a+4d=19 ...(1)

a

13

−a

8

=(a+12d)−(a+7d)=20

⇒5d=20

⇒d=4

On substituting the value of d in (1), we get

a+4×4=19

⇒a=3

Therefore the AP is

a,a+d,a+2d,a+3d...

3,7,11,15...