6 and l0terms is 44. Find A.P.The sum of first six terms of an A.P. is

1.	6 and l0terms is 44. Find A.P.The sum of first six terms of an A.P. is 42. The ratio of its 10th term to its 3erm is 1: 3. Calculate the first and the thirteenth term of the A.P0th[CBSE 2009 (O.D.)
Answer» S6 =42 a + 9d 1------------ = -------a + 29d 3 cross multiply we get3a + 27d = a +29 d2a - 2d = 0 ------------------ (1)its given thatsum of first six terms of an AP is 42therefore S6 = n/2 ( 2a + (n-1) d)42 = 6/2 ( 2a + (6-1) d)42 = 3 (2a + 5d )14 = 2a +5d2a +5d = 14 ------------------- (2) solve eq 1 and 22a - 2d = 02a +5d = 14 we getd= 2a = 213th term of AP= a + (n-1)d2+ (13-1) 2= 2+ 24=26

6 and l0terms is 44. Find A.P.The sum of first six terms of an A.P. is 42. The ratio of its 10th term to its 3erm is 1: 3. Calculate the first and the thirteenth term of the A.P0th[CBSE 2009 (O.D.)

Answer»

S6 =42

a + 9d 1------------ = -------a + 29d 3

cross multiply we get3a + 27d = a +29 d2a - 2d = 0 ------------------ (1)its given thatsum of first six terms of an AP is 42therefore

S6 = n/2 ( 2a + (n-1) d)42 = 6/2 ( 2a + (6-1) d)42 = 3 (2a + 5d )14 = 2a +5d2a +5d = 14 ------------------- (2)

solve eq 1 and 22a - 2d = 02a +5d = 14

we getd= 2a = 213th term of AP= a + (n-1)d2+ (13-1) 2= 2+ 24=26