24. The sum of first six terms of an.A.P. is 42. The ratio of its 1030

1.	24. The sum of first six terms of an.A.P. is 42. The ratio of its 1030th.term is 1:3. Calculate the first and 13th term of the A. Pto
Answer» S6 =42 a + 9d 1------------ = -------a + 29d 3 cross multiply we get 3a + 27d = a +29 d 2a - 2d = 0 ------------------ (1)its given thatsum of first six terms of ap is 42 therefore S6 = n/2 ( 2a + (n-1) d) 42 = 6/2 ( 2a + (6-1) d) 42 = 3 (2a + 5d ) 14 = 2a +5d 2a +5d = 14 ------------------- (2) solve eq 1 and 2 2a - 2d = 02a +5d = 14 we getd= 2a = 2---------------13th term of AP= a + (n-1)d 2+ (13-1) 2 = 2+ 24 =26

24. The sum of first six terms of an.A.P. is 42. The ratio of its 1030th.term is 1:3. Calculate the first and 13th term of the A. Pto

Answer»

S6 =42

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

cross multiply we get

3a + 27d = a +29 d

2a - 2d = 0 ------------------ (1)its given thatsum of first six terms of ap is 42

therefore

S6 = n/2 ( 2a + (n-1) d)

42 = 6/2 ( 2a + (6-1) d)

42 = 3 (2a + 5d )

14 = 2a +5d

2a +5d = 14 ------------------- (2)

solve eq 1 and 2

2a - 2d = 02a +5d = 14

we getd= 2a = 2---------------13th term of AP= a + (n-1)d

2+ (13-1) 2

= 2+ 24

=26