Ratio, Proportion, Indices, LogarithmMCQPYQ Jun 23Question 888 of 302
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If a3+b3+c3=0\displaystyle \displaystyle \sqrt[3]{a}+\sqrt[3]{b}+c3=0\displaystyle \sqrt[3]{c}=0 then the value of (a+b+c3)3\displaystyle \left(a+b+c3\displaystyle \frac{a+b+c}{3}\right)^3 is equal to

Select Your Answer (Keyboard: A, B, C, D)
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Correct Answer

✅ Option a — abc\displaystyle abc

All Options:

  • Aabc\displaystyle abc
  • B$9abc$
  • C1/(abc)\displaystyle 1/(abc)
  • D(1/9)abc\displaystyle (1/9)abc

Detailed Solution & Explanation

Let us define:
x=a3,y=b3,z=c3x = a3\displaystyle \sqrt[3]{a}, \quad y = b3\displaystyle \sqrt[3]{b}, \quad z = c3\displaystyle \sqrt[3]{c}
According to the problem, we are given:
x+y+z=0x + y + z = 0
Recall the standard algebraic identity: if the sum of three variables is zero (x+y+z=0\displaystyle x + y + z = 0), then the sum of their cubes is equal to three times their product:
x3+y3+z3=3xyzx^3 + y^3 + z^3 = 3xyz
Substitute the definitions of $x, y, z$ back into this identity:
\displaystyle &#x27; in math mode at position 150: …rt[3]{c}\right)̲重<br>" style="color:#cc0000">\left(a3\displaystyle \sqrt[3]{a}\right)^3 + \left(b3\displaystyle \sqrt[3]{b}\right)^3 + \left(c3\displaystyle \sqrt[3]{c}\right)^3 = 3 \left(a3\displaystyle \sqrt[3]{a} ⋅\displaystyle \cdot b3\displaystyle \sqrt[3]{b} ⋅\displaystyle \cdot c3\displaystyle \sqrt[3]{c}\right)\displaystyle 重&lt;br&gt;</span>a + b + c = 3 abc3\displaystyle \sqrt[3]{abc}<span class="katex-error" title="ParseError: KaTeX parse error: Can&#x27;t use function &#x27;' in math mode at position 47: …he equation by \displaystyle ̲3:<br>" style="color:#cc0000"><br>Now, divide both sides of the equation by 3\displaystyle 3:<br>\displaystyle \frac{a + b + c}{3} = \sqrt[3]{abc}<br>Tofindthefinalvalue,cubebothsidesoftheequation:<br><br>To find the final value, cube both sides of the equation:<br>\left(a+b+c3\displaystyle \frac{a + b + c}{3}\right)^3 = \left(abc3\displaystyle \sqrt[3]{abc}\right)^3 = abc$$
This matches **Option A**.
Hence, **Option A** is the correct answer.

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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