If three numbers form an arithmetic sequence, their sum is 15 and their sum of squares is 83, what are the three numbers

If three numbers form an arithmetic sequence, their sum is 15 and their sum of squares is 83, what are the three numbers

Let X be in the middle
Then let x-a, x, x + a
(x-a)+x+(x+a)=15
3x=15
x=5
(x-a)²+x²+(x+a)²=83
3x²+2a²=83
2a²=83-75=8
a=±2
So the three numbers are 3,5,7 or 7,5,3