Question

find the first 50 term and sum of first 50sum of AP 11 16 21 26

Answer 1

Answer:

Here A=11,D=16-11=5,A50=?,S50=?

We have An=A+(N-1)D

A50=11+(50-1)5

=11+49×5

=11+245

=256

Sn=N/2(2A+(N-1)D

=50/2(2×11+(50-1)5

=25(22+49×5)

=25(22+245)

=25(267)

=6675

Answer 2

a = 11, d = t2 - t1 = 16 - 11 = 5
Tn = a + ( n-1) d
T50 = 11 +( 50-1) 5
= 11 + 49×5
= 11 + 245
= 256
Sn = n/2 [ 2a +( n-1) d]
S50 = 50/2 [2×11 + ( 50-1) 5]
= 25 [ 22 + 245]
= 25 [ 267]
= 6675