If possible, express each of the following as the sum of a perfect square and a prime number. Give all possible answers and explain how you found them. . 21 28. 52. 68 . 13 . 20

4^2 + 5 = 21, 5^2 + 3 = 28, 7^2 + 3 = 52, 3^2 + 43 = 52, 7^2 + 19 = 68, 3^2 + 11 = 20, 1^2+19 = 20. I can't find a prime number and a perfect square that sums to 13.

Explanation:

these are primarily derived by finding the closest perfect square to a number and finding the difference to make the sum work, or finding the simplest prime number that will reduce the number which is a multiple of a perfect square.

you can use a^2+ b^2=c^2