Aptitude - Logarithm - Discussion
Discussion Forum : Logarithm - General Questions (Q.No. 6)
6.
| If log10 7 = a, then log10 |  |
1 |  |
is equal to: |
| 70 |
Answer: Option
Explanation:
|
= log10 1 - log10 70 | |||||
| = - log10 (7 x 10) | ||||||
| = - (log10 7 + log10 10) | ||||||
| = - (a + 1). |
Discussion:
34 comments Page 4 of 4.
Happiness said:
1 decade ago
How comes, log 10 is 0 should not it be 0.01, please anyone?
Prakash said:
1 decade ago
log (1/70) = log (1/7*10).
= log (1/7*1/10).
= log (1/7)+log (1/10).
= -log 7-log 10.
= -a-1.
= -(a+1).
= log (1/7*1/10).
= log (1/7)+log (1/10).
= -log 7-log 10.
= -a-1.
= -(a+1).
Sidhu said:
10 years ago
As we know that,
log10 1 = 0.
And
log x x =1.
log10 (1/70) = lo10 1 - log10 70.
= 0 - log10 70.
= - log10 (7 * 10).
= - (log10 7 + log10 10).
= - (a + 1).
Because log10 7 = a is given and log x x =1.
log10 1 = 0.
And
log x x =1.
log10 (1/70) = lo10 1 - log10 70.
= 0 - log10 70.
= - log10 (7 * 10).
= - (log10 7 + log10 10).
= - (a + 1).
Because log10 7 = a is given and log x x =1.
Nkayagwa Issa said:
10 years ago
Given,
Log7 = a,
Required to find = log10(1/70)
From logarithim of quotient,
Loga/b = loga - logb,
Therefore, log10(1/70) = log1 - log70.
= 0 - log70.
Since;
Any number to power one is 0 (logs laws).
= - log(10 + 7).
= -(1 + a).
Therefore, = -(1 + a). Because log7 is already given which is a and log10 = 1.
Log7 = a,
Required to find = log10(1/70)
From logarithim of quotient,
Loga/b = loga - logb,
Therefore, log10(1/70) = log1 - log70.
= 0 - log70.
Since;
Any number to power one is 0 (logs laws).
= - log(10 + 7).
= -(1 + a).
Therefore, = -(1 + a). Because log7 is already given which is a and log10 = 1.
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