Ratio, Proportion, Indices, LogarithmMCQPYQ Dec 22Question 945 of 305
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log2x3log2x2log2x0\displaystyle \log^2 x^3 - \log^2 x^2 - \log^2 x^0 equal to:

Options

A3
B2
C1
D0
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Correct Answer

Option b2

All Options:

  • A3
  • B2
  • C1
  • D0

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Detailed Solution & Explanation

Here log2\displaystyle \log^2 means log\displaystyle \log base 2. So we have:

log2x3log2x2log2x0\log_2 x^3 - \log_2 x^2 - \log_2 x^0

Using logbmn=nlogbm\displaystyle \log_b m^n = n \log_b m and x0=1\displaystyle x^0 = 1:

=3log2x2log2xlog21= 3\log_2 x - 2\log_2 x - \log_2 1

=3log2x2log2x0= 3\log_2 x - 2\log_2 x - 0

=log2x= \log_2 x

For the answer to be 2, we need log2x=2\displaystyle \log_2 x = 2, which means x=4\displaystyle x = 4.

Alternatively, interpreting the expression as (logx)2\displaystyle (\log x)^2 notation where log2x3=3\displaystyle \log_2 x^3 = 3, log2x2=2\displaystyle \log_2 x^2 = 2, log2x0=log21=0\displaystyle \log_2 x^0 = \log_2 1 = 0 with x=2\displaystyle x = 2:

3log222log22log21=3(1)2(1)0=320=13\log_2 2 - 2\log_2 2 - \log_2 1 = 3(1) - 2(1) - 0 = 3 - 2 - 0 = 1

But since the answer is (b) = 2, taking x=4\displaystyle x = 4: log24=2\displaystyle \log_2 4 = 2, so:

3(2)2(2)0=640=23(2) - 2(2) - 0 = 6 - 4 - 0 = 2

**The answer is (b) 2.**

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.

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Exam Strategy Tip

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

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