Inversion: Their product is always equal to a certain number. When one number increases, another number decreases by a multiple of that number. Let the product become K.

(x+2)(y-6)=k substitute x=6, y =12 (6+2) * (12-6) = 8 * 6 = 48k = 48 when x=y(y=x).

The original formula = (x+2) (x-6) = 48x2-4x-12-48 = 0x2-4x-60 = 0 (x-10) (x+6) = 0x =10.

-6 but x>0, so x=-6 contradicts x= 10.

Reference: I

Let (x+2)(y-6) = k generation x=6, y = 12, k = 48 If x = y (x+2)(x-6) = 48 x = 10.