Question

check whether the following sequence is in AP 9, 6, -1, -6, .....​

Answer 1

Step-by-step explanation:

Here

6-9 is not =-1-6

Thus it doesn't form AP

Answer 2

Step-by-step explanation:

here

a1 = 9, a2 = 6 ,a3 = -1

now

d1 = a2 - a1

= 6 -9 = -3

& d2 = a3 -a2

= -1 -6

= -7

since d1 (not equals to) d2

.: is not ap

......hope you understand......