SOLUTION: The sum of the first three terms of a G.P. is 42 and the fourth term exceeds first term by 42.

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Question 1135371: The sum of the first three terms of a G.P. is 42 and the fourth term exceeds first term by 42.
Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!


Your post should contain a question. Although it is obvious what your question probably is, it would be more polite if you asked it, instead of making us guess.

(1) a%2Bar%2Bar%5E2+=+42
(2) ar%5E3-a+=+42

ar%5E3-a+=+a%28r%5E3-1%29+=+a%28r-1%29%28r%5E2%2Br%2B1%29+=+42%28r-1%29+=+42
r-1+=+42%2F42+=+1
r+=+2

Substituting in (2),

a%288%29-a+=+42
7a+=+42
a+=+6

The GP is 6, 12, 24, 48, ...