Question

solve que. urgent solve

Answer 1

The ans is in the pic

Answer 2

$n = 50 \\ s10 = 210 \\ \frac{10}{2} (2a + 9d) = 210 \\ 10a + 45d = 210 \\ 2a + 9d = 42..................(1) \\ sum \: of \: last \: 15 \: terms = s50 - s35 \\ 2565 = \frac{50}{2} (2a + 49d) - \frac{35}{2} (2a + 34d) \\ 2565 = 25(2a + 49d) - 35(a + 17d) \\ 2565 = 50a + 1225d - 35a - 595d \\ 2565 = 15a + 630d \\ 171 = a + 42d....................(2) \\equation (2) \times 2 - (1) \\ 2a + 84d - 2a - 9d = 342 - 42 \\ 75d = 300 \\ d = 4 \\ a = 171 - 42 \times 4 \\ = 171 - 168 \\ = 3 \\ hence \: a.p. \\ 3,7,11,15.......$