Posted by Anonymous on .
The first term of an arithmetic sequence is 2. The first, third and eleventh terms are the first three terms of a geometric sequence. Determine the seventh term of the geometric sequence

Maths 
Steve,
I like it!
AS: 2 ... 2+2d ... 2+10d
GS: a ar ar^2
a = 2
ar = 2+2d  r = 1+d
ar^2 = 2+10d = 2r*r
2+10d = 2(1+d)^2
d = 3
AS: 2 5 8 11 14 17 20 23 26 29 32 . . .
GS: 2 8 32 128 512 2048 8192 . . .