Or using the first order condition and manipulating W/Z 2/W Unrigorously-just looking at the equation gives you the unimportance result (i.e, when z is small you expect this expression to be bigger) and the substitutes result (when the other goods are able to adjust a lot- you expect a bigger demand elasticity)Or using the first order condition and manipulating: Wj Zj /Zj /Wj = 1 Zj ? > i®j WiZi WjZj Wj Zi /Zi /Wj Unrigorously– just looking at the equation gives you the unimportance result (i.e., when z is small you expect this expression to be bigger) and the substitutes result (when the other goods are able to adjust a lot– you expect a bigger demand elasticity)