Question

find the sum of 13 terms of an ap. if the middle term is 42​

Answer 1

hope this finds you easy.....

Answer 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+