Answers

2016-01-25T23:41:24+05:30
A9=7*a2
a12=5a3+2

That means,
a9=(a+d)7
a12=5(a+2d)+2

That means,
a+8d=7a+7d, d=6a
a+11d=5a+10d+2,
d=4a+2,
2a=2,
a=1//
d=6a=6//

So first term is 1 & common difference is 6.
2 4 2