2nd term = a+d
7th term = a+6d
a+d + a+6d = 20
2a + 7d = 20 **
(a+d)/(a+6d) = 1/3
3a + 3d = a + 6d
2a = 3d ***
sub that into **
3d + 7d = 20
10d = 20
d = 2
then 2a = 6
a = 3
"Calculate The Sum Of The 1st Terms Of The G.P"
HUH? I thought we were dealing with an AP.
Isn't the sum of the first term just the first term???
The Ratio Of The 2nd Term To The 7th Term Of An A.P Is 1:3 And Their Sum Is 20.Calculate The Sum Of The 1st Terms Of The G.P
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