EquationsPYQ Jan 26Question 4250 of 155
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If α\displaystyle \alpha and β\displaystyle \beta are the roots of the equation 2x23x+1=0\displaystyle 2x^2 -3x + 1 = 0 then the equation whose roots are 1/α\displaystyle 1/\alpha and 1/β\displaystyle 1/\beta is:

Options

Ax2+3x+2=0\displaystyle x^2 + 3x + 2 = 0
Bx23x+2=0\displaystyle x^2 - 3x + 2 = 0
Cx2+3x2=0\displaystyle x^2 + 3x - 2 = 0
Dx23x2=0\displaystyle x^2 - 3x - 2 = 0
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Correct Answer

Option bx23x+2=0\displaystyle x^2 - 3x + 2 = 0

All Options:

  • Ax2+3x+2=0\displaystyle x^2 + 3x + 2 = 0
  • Bx23x+2=0\displaystyle x^2 - 3x + 2 = 0
  • Cx2+3x2=0\displaystyle x^2 + 3x - 2 = 0
  • Dx23x2=0\displaystyle x^2 - 3x - 2 = 0

Detailed Solution & Explanation

Given the quadratic equation: 2x23x+1=02x^2 - 3x + 1 = 0 Since α\displaystyle \alpha and β\displaystyle \beta are the roots of this equation, we can find their sum and product using the coefficients of the quadratic equation: α+β=ba=32=32\alpha + \beta = -\frac{b}{a} = -\frac{-3}{2} = \frac{3}{2} αβ=ca=12\alpha\beta = \frac{c}{a} = \frac{1}{2}
We need to find the equation whose roots are 1α\displaystyle \frac{1}{\alpha} and 1β\displaystyle \frac{1}{\beta}. Let the sum of the new roots be S\displaystyle S and their product be P\displaystyle P.
The sum of the new roots is: S=1α+1β=α+βαβS = \frac{1}{\alpha} + \frac{1}{\beta} = \frac{\alpha + \beta}{\alpha\beta} Substituting the values of α+β\displaystyle \alpha + \beta and αβ\displaystyle \alpha\beta: S=3/21/2=3S = \frac{3/2}{1/2} = 3
The product of the new roots is: P=1α×1β=1αβP = \frac{1}{\alpha} \times \frac{1}{\beta} = \frac{1}{\alpha\beta} Substituting the value of αβ\displaystyle \alpha\beta: P=11/2=2P = \frac{1}{1/2} = 2
The required quadratic equation is given by: x2Sx+P=0x^2 - Sx + P = 0 Substituting S=3\displaystyle S = 3 and P=2\displaystyle P = 2: x23x+2=0x^2 - 3x + 2 = 0 Hence, **Option B** is the correct answer.

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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