please explain how we went from the Blue to red

Question 2: (5 Marks) Prove that the population variance can be equal to the following: N = N El L( X , - M ) ' = N where N = population size How did we go from N -E ( x, - M) - Expand Blue to Red ? ? 02 I N El E (X2 + 12 - 2 X, ) - Take summation operator through N iMz N 02 x,? f _ M2)-2ME X,| X; N M X2 + (NM 2) - 21( Nu) 1 1= 1 02 N 1= 1 * 2 + NH 2 - 2 NH - 1 N 02 N 1= 1 X , ? - NH 21, 1 N