22221
21 = 1 x 21, 3 x 7, 7 x 3, 21 x 1
21 = 1 x 21, 3 x 7, 7 x 3, 21 x 1.
1 x 21, 3 x 7, 7 x 3, 21 x 1
1 x 21, 3 x 7, 7 x 3, 21 x 1
1 x 21, 3 x 7, 7 x 3, 21 x 1
1 x 21, 3 x 7 = 21
1, 3, 7, 21: 1 x 21, 3 x 7
1 x 21, 3 x 7.
1 x 63, 3 x 21, 7 x 9, 9 x 7, 21 x 3, 63 x 1.
1 x 21 = 21or3 x 7 = 21
1 x 21, 3 x 7.
Two specific cases of pairs of numbers whose product is 21 are: 1 x 21 and 3 x 7. The ratio of their sum to their difference is: 1 x 21 ... (21+1):(21 - 1) = 22:20 = 11 : 10, and 3 x 7 ... (3+7):(7-3) = 10:4 = 5 : 2. To find a general formula, let the larger number be x and the smaller be 21/x. Their sum is x + 21/x = (x^2 +21)/x Their difference is x - 21/x = (x^2 -21)/x Ratio of sum to difference is [(x^2+21)/x] / [(x^2-21)/x] = [(x^2+21)/x] * [x/(x^2-21)] = (x^2+21)/(x^2-21) Check: This formula produces the results found above.