Question

in ap sum of 1st 3rd 5th is 39 the sum of 2nd 4th 6th terms is 51 find the 10th term of the spaure and sum of 10 terms​

Answer 1

Answer:

» 10th term = ?, Sum of 10 terms = ?

=> 1st term = a, 3rd term = a + 2d,

5th term = a + 4d

» According to the first condition

› a + (a + 2d) + (a + 4d) = 39

› 3a + 6d = 39

› a + 2d = 13 .... (1)

=> 2nd term = a + d, 4th term = a + 3d,

6th term = a + 5d

› (a + d) + (a + 3d) + (a + 5d) = 51

› 3a + 9d = 51

› a + 3d = 17 .... (2)

from (1) & (2),

» d = 4, a = 5

Therefore,

» t10 = a + 9d

» t10 = 5 + 36

» t10 = 41

______________________________

» S10 = n/2 (t1 + t10)

» S10 = 5 (46)

» S10 = 230