Question

The sum of the first 20 terms of an AP is identical to the sum of the frst 22 terms ,if the common difference is -2 , find the first term
.

Answer 1

Answer:

41

Step-by-step explanation:

Sn= n/2[2a+(n-1)d]

given that, S20=S22

20/2[2a+(20-1)(-2)]=22/2[2a+(22-1)(-2)]

10(2a-38)=11(2a-42)

20a-380=22a-462

2a=82

a=41