Question

what is the common difference of ap. in which a21-a7= 84?l

__What is formula _& Explain ___​

Answer 1

see above attachment for solution !!

(ii) The formula to find common difference is

d = (an + 1 – an ) or d = (an – an-1).

• If the common difference is positive, then AP increases.
• If the common difference is negative then AP decreases.
• If the common difference is zero then AP will be constant.

hopefully its helped u dear :)