All questions of Logarithms for SSC CGL Exam
Steps to simplify log(75/16) - 2 log(5/9) + log(32/343):
1. Use logarithmic properties:
- log(a/b) = log(a) - log(b)
- log(a^b) = b*log(a)
2. Apply the properties:
- log(75/16) - 2 log(5/9) + log(32/343)
= log(75) - log(16) - 2(log(5) - log(9)) + log(32) - log(343)
3. Further simplify:
= log(75) - log(16) - 2log(5) + 2log(9) + log(32) - log(343)
= log(75) - log(16) - log(5^2) + log(9^2) + log(32) - log(343)
= log(75) - log(16) - log(25) + log(81) + log(32) - log(343)
= log(75*81*32) - log(16*25*343)
= log(194400) - log(137600)
= log(194400/137600)
= log(1.4142)
= log(2)
Therefore, the simplified form of log(75/16) - 2 log(5/9) + log(32/343) is log 2.
Given Exp.= log23 x log 32 x log34 x log43
= (log3 / log2) x ( log2 / log3) x (log4 / log3) x (log3 / log4) = 1
Required answer = [64 log10 2] + 1
= [ 64 x 0.3010 ] + 1
= 19.264 + 1
= 19 + 1
= 20
Understanding the Problem
To find log2 10, we can use the change of base formula. The relationship between logarithms of different bases is given by:
- log_a b = log_c b / log_c a
In this case, we can express log2 10 using base 10:
- log2 10 = log10 10 / log10 2
Now, we know that log10 10 = 1.
Calculating log2 10
Substituting the values we have:
- log2 10 = 1 / log10 2
Given that log10 2 = 0.3010, we can plug this value in:
- log2 10 = 1 / 0.3010
Next, we need to compute this division:
- log2 10 = 1000 / 301
This gives us the exact value of log2 10.
Conclusion
The correct answer is indeed option 'C':
- log2 10 = 1000 / 301
This method illustrates how to convert logarithms from one base to another using the change of base formula effectively.