Question

The sum of the 4the and 8the terms of an AP is 24 and the sum of the 6the and 10 terms is 44. Find the first terms of the AP.

Answer 1

Answer:

let the 1st term is a and common difference is b

then,

a+3b+a+7b=24

2a+10b=24

2(a+5b)=24

a+5b=24/2=12,. a=12-5b

again,a+5b+a+9b=44

2a+14b=44

2(a+7b)=44

a+7b=44/2=22

12-5b+7b=22

2b=22-12=10

b=10/2=5

a=12-5b

=12-5.5=12-25= -13

so the 1st term is -13