SOLUTION: The sum of three numbers in a.p is 12 and the sum of their squares is 66. what are the numbers

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Question 997811: The sum of three numbers in a.p is 12 and the sum of their squares is 66. what are the numbers
Answer by ikleyn(52788)   (Show Source): You can put this solution on YOUR website!
.
Let x  be a middle number,  then the first one is  x-d  and the third one is  x+d,  where  d  is the common difference.

The sum of three is  12.  It means that

(x-d) + x + (x+d) = 12,     or

3x = 12,     x = = 4.

The sum of squares is  66.  It means that

= ,     or

+ + = ,

+ = ,

= ,

= ,

= = ,   d = +/-.

Thus our progression is   1, 4, 7   or   7, 4, 1.


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