1-m^2/3m^2-m при m=2/3
1- 2/3^2 / 3 * 2/3^2 - 2/3= 1- 4/6 /3 * 4/6 - 2/3=1- 2/9 * 4/6 - 2/3=1- 8/54 -2/3= 48/54 - 2/3= 48/54 - 46/54=1/27