Question

first 22 words solve sn d= 7 and a+21d=249

Answer 1

Que :- Find the sum of First 22 terms in an A.P whose common Difference = 7 and 22nd term = 249.

Solution:-

=) a22 = 249

=) a + 21d = 249______________(1)

Substituting [ d = 7 ] in eq (1).

=) a = 249 - 21(7)

=) a = 249 - 147

=) a = 102.

Now,

sn = n/2 [ 2a + ( n-1)d ]

=) s22 = 22/2 [ 2 × 102 + 21 × 7 ]

=) s22 = 11 [ 204 + 147 ]

=) s22 = 11 × 29,988

=) s22 = 329,868.