If the sum of first 14 terms of an AP is 1050 and its first term is 10, then its 20th term is :

200

Sum of first 14 terms of an AP (Sn) = 1050

n = 14

First term ( a ) = 10

We know,

Sn = \(\frac{n}{2}\)[ 2a + (n-1)d]

1050 = \(\frac{14}{2}\)[ 2 × 10  + (14-1)d]

1050 = 7[ 20  + 13d]

1050 = 140 + 91d

d = 10

Now,

20th term = a + ( n - 1 ) d

= 10 + ( 20 - 1 ) × 10

= 10 + 190

= 200