7.9 In Example 7.2 we showed that with two goods the price elasticity of demand of a compensated demand curve is given by es X,PX
(1 sX), where sX is the share of income spent on good X and is the substitution elasticity. Use this result together with the elasticity interpretation of the Slutsky equation to show that:

a. if
1 (the Cobb-Doublas case), eX,PX eY,PY
2.

b. if  1 implies eX,PX eY,PY  2 and  1 implies eX,PX eY,PY  2. These results can easily be generalized to cases of more than two goods.