EquationsMCQMTP Oct 21Question 1084 of 221
All Questions

The roots of equation 9x26.3x+1=0\displaystyle 9x^2 - 6.3x + 1 = 0 are

Options

A2\displaystyle 2
B0\displaystyle 0
C2\displaystyle -2
D2\displaystyle 2
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Correct Answer

Option c2\displaystyle -2

All Options:

  • A2\displaystyle 2
  • B0\displaystyle 0
  • C2\displaystyle -2
  • D2\displaystyle 2

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Detailed Solution & Explanation

The expression as written (9x26.3x+1=0\displaystyle 9x^2 - 6.3x + 1 = 0) contains a common typographical distortion from the MTP Oct 2021 series. The actual mathematical question is exponential:
9x+263x+1+1=09^{x+2} - 6 \cdot 3^{x+1} + 1 = 0
Let's solve this exponential equation step-by-step:
1. Express the terms with base 3:
9x+2=(32)x+2=32x+4=34(3x)2=81(3x)29^{x+2} = (3^2)^{x+2} = 3^{2x+4} = 3^4 \cdot (3^x)^2 = 81 \cdot (3^x)^2
63x+1=633x=183x6 \cdot 3^{x+1} = 6 \cdot 3 \cdot 3^x = 18 \cdot 3^x
2. Substitute y=3x\displaystyle y = 3^x:
81y218y+1=081y^2 - 18y + 1 = 0
3. Recognize the perfect square trinomial:
(9y1)2=0    9y1=0    y=19(9y - 1)^2 = 0 \implies 9y - 1 = 0 \implies y = \frac{1}{9}
4. Solve for x\displaystyle x:
3x=19=32    x=23^x = \frac{1}{9} = 3^{-2} \implies x = -2
Thus, the mathematical solution is x=2\displaystyle x = -2, which corresponds to Option c.

**Option c**

About This Chapter: Equations

Paper

Paper 3: Quantitative Aptitude

Weightage

4-6 Marks

Key Topics

Linear, Quadratic and Cubic Equations

This chapter covers Linear, Quadratic and Cubic Equations and is part of Paper 3: Quantitative Aptitude in the CA Foundation exam.

View Official ICAI Syllabus

Exam Strategy Tip

This topic carries 4-6 Marks weightage. Focus on understanding core concepts rather than memorizing.

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