2. Find the marginal rate of substitution between capital and labour for the CES production function, and show that the elasticity of substitution is -, independent of r and w. The CES function is more general than the Cobb-Douglas function, since the particular value = 1 (or the limit for 1) corresponds to the Cobb-Douglas function. Nevertheless, we have chosen to work with the more special Cobb-Douglas function, partly for simplicity, but also for the reason appearing from the answers to the next two questions.