10.資本結構相關問題：(12分，每小題2分)

(1) 請以中文簡要說明 Modigliani and Miller 之資本結構無關論的定理 1：
Proposition 1: Firm value is determined on the left-hand side of the balance sheet by real asset — not by the proportions of debt and equity securities issued to buy the assets.
(2) Modigliani and Miller 之資本結構無關論的 Proposition 2 : The expected rate of return on the common stock of a levered firm increases in proportion to the debt-equity ratio. 此定理之意含可具體化為：$r_E = r_A + (r_A - r_D) \frac{D}{E}$，請依據上式，分析公司增加舉債可能導致 $r_E$ 上升及下降的原因。