Unit 8, Lesson 2 – Logs (evaluate and inverse)
Write each equation in logarithmic form.
1.
92 = 81
2.
252 = 625
3.
170 = 1
5 2 
4.
1
25
Write each equation in exponential form.
5. log4256 = 4
6. log71 = 0
7. log232 = 5
8. log 10 = 1
Evaluate each logarithm.
9.
log216
10. log6216
11. log3
1
9
12. log 100,000
Find the inverse of the function.
13. y = log4 X
14. y = log 10X
15. y = log (x – 2)
16. y = log5 X 2
Unit 8, Lesson 2 – Logs (evaluate and inverse)
17. a) Suppose that the number of bacteria in a lab dish at any time t hours after the start of an
experiment is given by the function B(t) = 500 (10 0.3t ). Show how to use logarithms to
find the time when there will be 10,000 bacteria in the lab dish.
b) Suppose that the value (in millions of dollars) of the Detroit Tigers baseball
team at any time t years after 2006 is given by the function V(t) = 450 (10 0.02t ). Show
how to use logarithms to find the time when that investment will be worth $1 billion.
c) Suppose that the amount of medicine (in mg) active in a patient’s blood at any time t
hours after an injection is given by the function M(t) = 500 (10 –0.071t ). Show how to use
logarithms to find the time when only 25 mg of the medicine remain active.