SOLUTION: Hi, im finding difficulty trying to answer these two questions, help would be much appreciated, thank you very much. (a)Find a and b if a,1,a+b forms a geometric progression and

Question 973410: Hi, im finding difficulty trying to answer these two questions, help would be much appreciated, thank you very much.
(a)Find a and b if a,1,a+b forms a geometric progression and b,1/2,a-b forms an arithmetic progression
(b)Show that if the first, second and fourth terms of an arithmetic progression form a geometric sequence, then either the sequence is a constant sequence, or the terms are the positive integer multiples of the first term.
Answer by josgarithmetic(39620) (Show Source): You can put this solution on YOUR website!
(b):
First four terms, a, a+d, a+2d, a+4d

This arrangement is geometric progression: , , ;
Let r be the common ratio.
, ,

Try forming equations from those ratio related relationships.
and

What happens if solve these last two equations for a and d?
That is the strategy to try, but I have not yet done further.
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