Elitmus
Exam
Numerical Ability
Log and Antilog
if z=(log(base a)(log(base b)(a)))/(log(base b)(log(base a)(b)))
simplify z
Read Solution (Total 6)
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- Answer z= - log(base a)(b)
- 10 years agoHelpfull: Yes(12) No(0)
- Z = [ log{log(a)/log(b)}/log(a) ] / [log{log(b)/log(a)}/log(b)]
Z= (log a)^3 / (log b)^3
Z = 3 log a / 3 log b
so ans is Z = log (base b) a - 10 years agoHelpfull: Yes(12) No(3)
- Answer: z = log(base a) (1/b)
Formula:
1)Log(base a)(b) = log(b)/log(a)
2)Log(x/y) = logx - logy
We have,
Z = [ log{log(a)/log(b)}/log(a) ] / [log{log(b)/log(a)}/log(b)]
As log(logb / loga) = log(logb) - log(loga)
=> z = [logb / loga] * [ {log(loga) - log(logb)} / {log(logb) - log(loga)}]
=> z = -log(b) / log(a)
=> z = log(base a) (1/b) - 10 years agoHelpfull: Yes(5) No(2)
- We cannot directly use the log a / log b form as the given problem is log of log format.
One way of solving the problem is assuming the relation between a and b.
Let a = b power n
a = b ^ n
Now the numerator is loga(logba) = loga(logb(b^n))
As the power goes out it will become loga(nlogbb)
As logbb=1, the entire numerator can be simplified as loga(n)
Now the denominator is logb(logab)
As we assumed a = b ^ n, denominator can be written as
= logb(logb^n(b))
As the power is for the base, it will become reciprocal and goes out it will become logb(1/nlogbb)
As logbb=1, the entire numerator can be simplified as logb(1/n)
As 1/n can be written as n power –1, the denominator can be simplified as –logb(n)
Now, we can use loga / log b form for further simplification.
Numerator is loga(n) = log n/ log a
Denominator is –logb(n) = –log n/ log b
Now by cancelling out log n in numerator and denominator, we get –log b/ log a
This can be written as –loga(b)
–loga(b) is the answer.
- 10 years agoHelpfull: Yes(4) No(0)
- log a^ (log b^a))/log b^ ( log a^b)
(log b^a) (log b) log a log b * log a
= --------------- * --------------- = ---------------- * -----------------------
log a (log a^b) log b* log a log a
=1 - 10 years agoHelpfull: Yes(0) No(1)
- z=(log(base a)(log(base b)(a)))/(log(base b)(log(base a)(b)))
=> z=[log(base b)(a))/log(a)]*[log(b)/(log(base a)(b))]
=> z=[log(a)/{log(a)*log(b)}]*[{log(b)*log(a)}/log(b)]
=> Z=log(a)/Log(b)
=> Z=log(base b) (a) .....Ans - 9 years agoHelpfull: Yes(0) No(1)
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