Question

in an a.p 19th term is 52 and 38th term is 128,find sum of first 56 terms​

Answer 1

Answer:

A+18d=52

a+37d=128

______________

19d=76, d=76/19 = 4

a= -20

then sum of 56terms

=(2(-20)+55(4))56/2

=180×28

=5040

Answer 2

a+18d=52

a+37d=128

______________

19d=76, d=76/19 = 4

a= -20

then sum of 56terms

=(2(-20)+55(4))56/2

=180×28

=5040