The rate of a chemical reaction varies, depending on the initial amount of a certain compound. In general, the reaction rate, V, can be expressed by the following formula, where k is a positive constant, and a is the initial amount of the compound. V(x)equalskx(aminusx) The positive constant, k, for one such reaction is 0.4, and the initial amount of the compound, a, is 22. For what value of x is the rate a maximum?