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1. |
Find the value of a if the graph of the exponential function y = a· 2x passes through the point A(3, 128). |
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A. |
16 |
B. |
4 |
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C. |
32 |
D. |
8 |
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Hint |
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2. |
Solve log5 ( x + 2) + log5 ( 2x - 1) = 2. |
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A. |
3 |
B. |
 , 3 |
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C. |
no solution |
D. |
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Hint |
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3. |
Find ln 6.21 to four decimal places. |
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A. |
0.7931 |
B. |
2.7183 |
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C. |
1.8262 |
D. |
497.7013 |
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Hint |
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4. |
Solve 4x = 22 to three decimal places. |
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A. |
3.961 |
B. |
3.414 |
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C. |
5.500 |
D. |
2.230 |
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Hint |
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5. |
Business An analyst estimates that the computers his company just bought will depreciate at a rate of 25% per year. At this rate, approximately how long will it take a computer to depreciate to 30% of its original value? |
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A. |
3 years |
B. |
4 years |
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C. |
5 years |
D. |
10 years |
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Hint |
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6. |
Which of the following represents exponential decay? |
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A. |
 |
B. |
 |
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C. |
 |
D. |
 |
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Hint |
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7. |
Solve log 3 x < 4. Check your solution. |
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A. |
0 < x < 81 |
B. |
x < 81 |
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C. |
x < 64 |
D. |
0 < x < 64 |
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Hint |
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8. |
Solve log 5 (5x – 2) > log 5 (2x + 10). |
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A. |
x < 4 |
B. |
0 < x < 4 |
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C. |
x > 625 |
D. |
x > 4 |
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Hint |
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9. |
Use the fact that log 5 8  1.29 and log 5 10 1.43 to approximate the value of log 5 80. |
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A. |
1.11 |
B. |
2.72 |
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C. |
16 |
D. |
1.84 |
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Hint |
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10. |
Suppose black coffee has a pH of 5 and milk of magnesia has a pH of 10. How many times more hydrogen ions are in black coffee than in milk of magnesia? (pH = –log[H+], where H+ is the substance's hydrogen ion concentration in moles per liter) |
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A. |
2 times |
B. |
100 times |
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C. |
5 times |
D. |
100,000 times |
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Hint |
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11. |
Solve 4 – 2e4x = 1. |
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A. |
–0.10 |
B. |
–0.41 |
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C. |
0.10 |
D. |
0.41 |
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Hint |
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12. |
Two cities have insect problems. The insects in City A increase exponentially according to the equation y = 120,000e0.04t. The insects in City B increase exponentially according to the equation y = 90,000e0.08t. In 15 years, which city will have more insects, and by approximately how much? |
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A. |
City B, by about 30,000 |
B. |
City B, by about 80,000 |
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C. |
City A, by about 80,000 |
D. |
City A, by about 30,000 |
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Hint |
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