Question

The sum of first six terms of an
a.P. Is 42. The ratio of its 10th term to its 30th term is 1:3. Find the first term of the
a.P

Answer 1

Step-by-step explanation:

s6=42

6/2(2a+(6-1)d)=42

3(2a+5d)=42

2a+5d=14

a10/a30=1/3

a+9d/a+29=1/3

3a+27d=a+29d

2a=2d

a=d

2a+5d=14

2d+5d=14

7d=14

d=2

a=d

a=2