The sum of the first three consecutive terms in AP is 21 and the last to has ratio 6:1. Find the numbers

3 answers

a + a+d + a+2d = 21
3 a + 3 d = 21
a+d = 7
d = 7-a

(a+2d) / (a+d) =6
(a+ 14-2a) / 7 = 6
(14-a) = 42
a = - 28
d = 7+28 = 35

-28 , 7 , 42

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check
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sum = 21
42/7 = 6 sure enough
The phrase " .... and the last to has ratio 6:1 " makes no sense.

Anonymous assumed the ratio of 6:1 was the third term to 2nd term, I don't know why.
If you meant that the ratio of the last two terms was 6:1, then
we could get
(a+d)/(a+2d) + 6 , depending on who's first..
I assumed that the w was missing from
" .... last tWo has ratio ..."