Suppose $18,000 is invested in an account that earns 4.3% interest. (a) Write an equation for a function V that gives the value of the account after t years if interest is compounded monthly. V(t) = (b) Compute V'(2.9). (Round your answer to two decimal places.) per year Interpret your answer. After 2.9 years, the value of the account is increasing at a rate of $ per year.