Question

find the sum of first 10 terms of the ap whose 4th term is -15and 9th term is -30

Answer 1

Answer:

- 33

Step-by-step explanation:

we have ,

4th termas - 15 and 9th termas- 30

so

a+3d=- 15

a+8d=- 30

whice gives d=- 3

so by useing formula

an=a+n- 1×d

since we got a=- 6

an=- 6+9×- 3

we get an =- 33

so an10=- 33