For each of the following investments, compute the IRR.
a. The net cash flows are $-12,000 in the first year and +$15,000 in the second year. (Use the formula for two-period investments given in the text.)
b. The net cash flows are $-10,000 in the first year, +$5,000 in the second year, and +$6,000 in the third year. (Use the quadratic formula.)
c. The net cash flows are the same as in problem 10. (Use either the search method illustrated in Worked-Out Problem 10.5, or the automatic search feature of a spreadsheet program.)