Question

Find the sum of first 10 terms of A.P. whose nth term am = 9 - 5n.​

Answer 1

Answer:

nth term = 9-5n

1st term= 9-5×1= 9-5 =4

10 th term = 9-5×10 = 9 - 50 = -41

The sum of first 10 term is

$= \frac{1}{n} \ \: time \: (first \: term \: + last \: term)$

$= \frac{1}{10} \times (4 + ( - 41))$

$= \frac{1}{10} \times ( - 37)$

$= - \frac{37}{10}$