ax^2 = a(x+2) - 2

ax^2 = ax + 2a - 2

ax^2 - ax = 2a - 2

a*x(x - 1) = 2(a - 1)

x(x - 1) = 2 (a - 1) / a

x = 2 (a - 1) / a / (a - 1)

x = 2 / a