Question

11. If the sum of the first 14 terms of an AP is 1050 and its first term is 10, find the 20th term.

Standard:- 10

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Answer 1

Hey Mate !!

Thanks for the question.

Given,

Sum of first 14 terms is 1050

Sn = n/2 ( 2a + ( n - 1)d

1050 = 14/2 ( 2 (10) + ( 14-1)d )

1050 = 7 ( 20 + 13d )

1050 = 140 + 91d

1050 - 140 = 91d

910 = 91d

d = 910/91

d = 10

Therefore, 20th term = a + 19d= 10 + 190 = 200

HOPE THIS HELPS U...

Answer 2

Heya !!!




Sum of first 14th term = 1050



Sn = N/2 × [ 2A + ( N -1) × D ]



S14 = 14/2 × [ 2A + ( 14 - 1) × D ]



=> 7 ( 2A + 13D ) = 1050



=> 7 ( 2 × 10 + 13D ) = 1050



=> 7 ( 20 + 13D ) = 1050


=> 140 + 91D = 1050


=> 91D = 1050-140


=> 91D = 910


=> D = 910/91


=> D = 10


Therefore,



20th term = A + 19D


=> 10 + 19 × 10


=> 10 + 190


=> 200 ...



★ HOPE IT WILL HELP YOU ★