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13. Solve for x: x2 2x + 2xex => 8ex 14. Solve for X: log3 (x - 8) + log3 x - 2 15. A sum of $5000 is invested at 8.5% per year, compounded semi-annually. a) Find the amount in the account after 1.5 years. b) How long will it take for the account to grow to be $7000? c) If compounded continuously, how long would it take for the account to reach $7000? 16. The stray-cat population in a small town grows exponentially. In 1999, the town had 30 stray cats and the relative growth rate is 15% per year. Find the number of years it takes for the stray cat population to reach 500. 17. Uranium-234 (U-234) has a half-life of 270,000 years. If you started with 10 milligrams of the U-234, how many milligrams will be left after 10,000 years