NAME
DATE
7-6
PERIOD
Skills Practice
Common Logarithms
Use a calculator to evaluate each expression to the nearest ten-thousandth.
1. log 6 0.7782
2. log 15 1.1761
3. log 1.1 0.0414
4. log 0.3 -0.5229
Solve each equation or inequality. Round to the nearest ten-thousandth.
{v | v ≤ - −12 }
5. 3x > 243 {x | x > 5}
1
6. 16v ≤ −
7. 8 p = 50 1.8813
8. 7y = 15 1.3917
9. 53b = 106 0.9659
4
10. 45k = 37 0.5209
11. 127p = 120 0.2752
12. 92m = 27 0.75
13. 3r - 5 = 4.1 6.2843
14. 8 y + 4 > 15 {y | y > -2.6977}
15. 7.6 d + 3 = 57.2 -1.0048
16. 0.5t - 8 = 16.3
18. 5x
2
= 10 ±0.6563
+1
Express each logarithm in terms of common logarithms. Then approximate its
value to the nearest ten-thousandth.
19. log3 7
21. log2 35
log 7
log 3
log 35
− ; 5.1293
log 2
− ; 1.7712
20. log5 66
22. log6 10
log 66
log 5
log 10
− ; 1.2851
log 6
− ; 2.6032
23. Use the formula pH = -log [H+] to find the pH of each substance given its
concentration of hydrogen ions. Round to the nearest tenth.
a. gastric juices: [H+] = 1.0 × 10-1 mole per liter
1.0
b. tomato juice: [H+] = 7.94 × 10-5 mole per liter 4.1
c. blood: [H+] = 3.98 × 10-8 mole per liter
7.4
d. toothpaste: [H+] = 1.26 × 10-10 mole per liter 9.9
Chapter 7
42
Glencoe Algebra 2
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
2
17. 42x = 84 ±1.0888
3.9732