Exercise 6.9.9 Show that (a) 123 = 12 1323 1 2 13 1

Exercise 6.9.9 Show that

(a) ρ12·3 = ρ12 −  ρ13ρ23 1 − ρ2 13



1 − ρ2 23

(b) ρ12·34 = ρ12·4 − ρ13·4ρ23·4 

1 − ρ2 13·4



1 − ρ2 23·4

.