Answer:
Step-by-step explanation:
First we find n:
Tn = a+ (n-1)d
Here,
a=1 ,Tn =57
d=2 ( difference between numbers is 2)
Now,
57 = 1 + (n-1)2
57 = 2n -1
58/2 = n
Or n = 29
Now, We find sum :
Sn = n/2 { a+Tn}
= 29/2 { 1 + 57 }
= 29/2 ( 58)
= 29 x 29
= 841
