Question

K+1, 2K+2, 13 is an arithmetic sequence . Find K ? ​

Answer 1

a1 = k+1

a2= 2k+2

a3= 13

d= a2-a1

 = 2k+2-(k+1)

 = 2k +2 -k -1

d = k-1                   -(1)

d=a3-a2

 =13-(2k+2)

 =13-2k-2

d = 11-2k                -(2)

From (1) and (2)

k-1=11-2k

k+2k=11+1

3k=12

k=12/3

k=4

Answer: k=4

Answer 2

Answer:

Step-by-step explanation:

Ap is k+ 1, 2k+ 2,13...

Now, a= k+1 (1)

a2 = 2k+2

a+d = 2k+ 2( as a2= a+d) (2)

a3= 13 ;;; a+2d= 13( as a3= a+2d)

(3)

By solving equation 2 and 3 by elimination method