4. There is a shortcut version for calculating the sample variance given by the following formula: Show that this is equivalent to the definition given in the lectures. In other words, show that: ==((2x+) - CE"1") = (3x -x)) --- ((3x). (cym) i= 1 Bonus: Show that the shortcut version of the sample covariance given below is equivalent to the definition given in lectures. sv=-=((2xx)(..)ELY)