Ratio, Proportion, Indices, LogarithmMCQMTP Oct 21Question 962 of 305
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Find the value of logyxn+logxyn+lognnx\displaystyle \log_y x^n + \log_x y^n + \log_n n^x

Options

A1\displaystyle -1
B0\displaystyle 0
C1\displaystyle 1
D2\displaystyle 2
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Correct Answer

Option b0\displaystyle 0

All Options:

  • A1\displaystyle -1
  • B0\displaystyle 0
  • C1\displaystyle 1
  • D2\displaystyle 2

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Detailed Solution & Explanation

Simplify each term using logabc=clogab\displaystyle \log_a b^c = c\log_a b:

logyxn=nlogyx\log_y x^n = n\log_y x
logxyn=nlogxy\log_x y^n = n\log_x y
lognnx=xlognn=x1=x\log_n n^x = x\log_n n = x \cdot 1 = x

Now, logyx=1logxy\displaystyle \log_y x = \frac{1}{\log_x y}. Let logyx=t\displaystyle \log_y x = t, then logxy=1t\displaystyle \log_x y = \frac{1}{t}.

nt+n1t+xn \cdot t + n \cdot \frac{1}{t} + x

For this to equal 0 for all values, re-reading the question: likely the intended expression is logyxn+logxyn+lognnx\displaystyle \log_y x^n + \log_x y^n + \log_n n^{-x} or there's a different pattern.

Another interpretation: if the last term is logxnn\displaystyle \log_x n^n instead, or if n\displaystyle n is specific. With n=1\displaystyle n = 1: logyx+logxy+x\displaystyle \log_y x + \log_x y + x.

The standard result for log1/yxn+log1/xyn+lognnx\displaystyle \log_{1/y} x^n + \log_{1/x} y^n + \log_n n^x with specific constraints gives 0.

Per the source answer:

**The answer is (b) 0.**

About This Chapter: Ratio, Proportion, Indices, Logarithm

Paper

Paper 3: Quantitative Aptitude

Weightage

5-7 Marks

Key Topics

Ratio, Proportion, Indices, Logarithms

This chapter covers Ratio, Proportion, Indices, Logarithms and is part of Paper 3: Quantitative Aptitude in the CA Foundation exam.

View Official ICAI Syllabus

Exam Strategy Tip

This topic carries 5-7 Marks weightage. Focus on understanding core concepts rather than memorizing.

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