In exercise 15 of Chapter 7 the reader was asked to verify that a stock or
security itself satisfies the Black-Scholes PDE (6.14). Now suppose that
a portfolio consists of a linear combination of options and shares of the
underlying security. The portfolio contains a short position in a European
call option and a long position in the security (hedged appropriately as
described in the previous section). Thus the net value V of the portfolio is