There are three numbers in an equal ratio sequence, and the sum is 21. If the third number subtracts 9, then the three numbers will become an equal difference sequence, and the three numbers can be calculated I figured out that the middle number was four,

There are three numbers in an equal ratio sequence, and the sum is 21. If the third number subtracts 9, then the three numbers will become an equal difference sequence, and the three numbers can be calculated I figured out that the middle number was four,

If a1 + A2 + a3 = 21a1, A2, a3-9 become arithmetic sequence, then a1 + A2 + (a3-9) = 3a2, that is, A2 = 4 and A1, A2, A3 become arithmetic sequence, that is, a1 + 4 + A1 * (4 / A1) ^ 2 = 21a1 + 16 / A1 = 17a1 ^ 2-17a1 + 16 = 0, that is, A1 = 1 or A1 = 16. When A1 = 1, A2 = 4, A3 = 16, when A1 = 16, A2 = 4, A3 = 1, that is, three numbers are 1, 4, 16