find the sum of 13 terms of an ap. if the middle term is 42
Answers
Answered by
3
hope this finds you easy.....
Attachments:
Answered by
2
Answer:
n=13
in 13 terms middle term is 42 so
the middle most term is 7 the term
a+6d=a7
a7=42
a+6d=42
a=42-6d---------(1)
an=a+n-1*d
an=42-6d+12*d
an=42+6d
42=6d
d=7 substitute in a+6d
a+6*7=42
a=0
sn= n/2*a+an
sn=13/2*0+
Similar questions