As in chapter 14 bu is the beta of an unlevered firm; b is the beta of levered firm. Because debt is not riskless, it has a beta, bD. Although the Ehrhardt and Daves analysis was done including corporate taxes and growth, neither of these expressions has the corporate tax rate or the growth rate in it. This means the expression for the levered required rate of return, Equation 17-15, is exactly the same as MM’s expression for the levered required rate of return without taxes, Equation 17-2. And the expression for the levered beta, Equation 17-16, is exactly the same as Hamada’s equation (with risky debt), but without taxes. The reason the tax rate and the growth rate drop out of these two expressions is that the growing tax shield is discounted at the unlevered cost of equity, rsU, not at the cost of debt as in the MM model. The tax rate drops out because no matter how high the level of T, the total risk of the firm will not be changed since the unlevered cash flows and the tax shield are discounted at the same rate. The growth rate drops out for the same reason: An increasing debt level will not change the riskiness of the entire firm no matter what rate of growth prevails.