NAME
DATE
3-4
PERIOD
Practice
Exponential and Logarithmic Equations
Solve each equation.
1. 5x = 125 x-2 3
(9)
1
3. −
x+3
= 27x
2. log6 x + log6 9 = log6 54
6
-−
6
4. e2x - ex - 6 = 0 ≈1.099
5
1
6. ln −
e = x -1
5. logx 64 = 3 4
17
2
8. 3e4x - 9e2x - 15 = 0 ≈0.7167
7. ln (2x - 1) = ln 16 −
40
7
9. ln (x - 5) + ln 4 = ln x - ln 2 −
10. 4x + 2 = 6-2x - 3 ≈-1.639
12. 6 ln (x + 2) - 3 = 21 ≈52.6
11. 6e6x - 17e 3x + 7 = 0
≈0.28 and ≈-0.23
13. 4e 2x - 13e x + 9 = 0
14. log (2x + 1) + log (x − 4) = log (2x2 - 4)
0 and ≈0.811
no solution
16. log5 (x + 4) + log5 x = log5 12 2
17. log (x + 1) + log (x − 3) = log (6x2 - 6)
18. ln 0.04x = -8
≈0.008
no solution
Solve each equation. Round to the nearest hundredth.
19. 2 9x = 1210 1.14
20. 4 3x = 1056 1.67
21. 5 x + 3 - 4 = 19 −1.05
22. 3 x − 8 + 2 = 38 11.26
23. 6 2x - 1 = 18 1.31
24. 2 3 + 2x = 130 2.01
25. BANKING Ms. Cubbatz invested a sum of money in a certificate of
deposit that earns 8% interest compounded continuously. The formula
for calculating interest that is compounded continuously is A = Pe rt.
If Ms. Cubbatz made the investment on January 1, 2005, and the
account was worth $12,000 on January 1, 2009, what was the original
amount in the account? $8713.79
26. FINANCIAL LITERACY If $500 is deposited in a savings account
providing an annual interest rate of 5.6% compounded quarterly,
how long will it take for the account to be worth $750? 7.29 years
Chapter 3
22
Glencoe Precalculus
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
15. 2 -4x + 1 = 3 2x - 3 ≈0.80