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OverviewExercise"Two things are infinite: the universe and human stupidity; and I'm not sure about the universe."
- Albert Einstein
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| 6. |
| If log10 7 = a, then log10 |
 |
1 |
 |
is equal to: |
| 70 |
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Answer: Option A
Explanation:
| log10 |
|
1 |
|
| 70 |
|
= log10 1 - log10 70 |
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= - log10 (7 x 10) |
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= - (log10 7 + log10 10) |
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= - (a + 1). |
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| 7. |
If log10 2 = 0.3010, then log2 10 is equal to:
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Answer: Option E
Explanation:
| log2 10 = |
1 |
= |
1 |
= |
10000 |
= |
1000 |
. |
| log10 2 |
0.3010 |
3010 |
301 |
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| 8. |
If log10 2 = 0.3010, the value of log10 80 is: |
| A. |
1.6020 | B. |
1.9030 | | C. |
3.9030 | D. |
None of these |
Answer: Option C
Explanation:
| log10 80 |
= log10 (8 x 10) |
|
= log10 8 + log10 10 |
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= log10 (23 ) + 1 |
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= 3 log10 2 + 1 |
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= (3 x 0.3010) + 1 |
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= 1.9030. |
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| 9. |
If log10 5 + log10 (5x + 1) = log10 (x + 5) + 1, then x is equal to:
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Answer: Option C
Explanation:
log10 5 + log10 (5x + 1) = log10 (x + 5) + 1
 log10 5 + log10 (5x + 1) = log10 (x + 5) + log10 10
log10 [5 (5x + 1)] = log10 [10(x + 5)]
5(5x + 1) = 10(x + 5)
5x + 1 = 2x + 10
3x = 9
x = 3.
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| 10. |
| The value of |
|
1 |
+ |
1 |
+ |
1 |
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is: |
| log3 60 |
log4 60 |
log5 60 |
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Answer: Option B
Explanation:
| Given expression |
= log60 3 + log60 4 + log60 5 |
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= log60 (3 x 4 x 5) |
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= log60 60 |
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= 1. |
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