Maths brain games

Maths brain games December Tuesday 10

Is the one in middle 9 16 12 and not 9 10 12?

4 = 2^2  6 =2^2 +2
9 = 3^2 6 =3^2 -3

9 = 3^2  12 = 3^2 +3
16 = 4^2 12 = 4^2 -4

16 = 4^2 20 4^2 + 4
25 = 5^2 20 = 5^2  - 5

Then answer would be 25