posted by Anonymous .
in an arthmetic progression or series,the 13th term is 27 and the 7th iterm is 3 times the 2nd term ,find first term the common difference the sum of rhe squence
13th term is 27 --- a + 12d = 27
the 7th iterm is 3 times the 2nd term --> a+6d = 3(a+d)
a+6d = 3a + 3d
2a = 3d
a = 3d/2
sub into the first equation
3d/2 + 12d = 27
d = 2
then a = 3(2)/2 = 3
I will let you finish it for the sum, you did not say how many terms you want to add.