1,2. construct a bull spread and draw the payoff's figure. Then prove it through the figure. Should be very easy, an entry level mathematical problem
3. consider the payoff function CT(ST,K)=max(ST-K,0). It is a homogenous function (degree 1). Suppose Ct(St,K) is not homogenous, let's say aCt(St,K)>Ct(aSt,aK), you can short "a" share of option Ct(St,K) and long a synthetic option with strike aK ...
1,2. construct a bull spread and draw the payoff's figure. Then prove it through the figure. Should be very easy, an entry level mathematical problem
3. consider the payoff function CT(ST,K)=max(ST-K,0). It is a homogenous function (degree 1). Suppose Ct(St,K) is not homogenous, let's say aCt(St,K)>Ct(aSt,aK), you can short "a" share of option Ct(St,K) and long a synthetic option with strike aK and underlying is "a" share of St. At maturity, aCT(ST,K) should be equal to CT(aST,aK), you make the arbitrage profit aCt(St,K)-Ct(aSt,aK)