EquationsMCQMTP June 24 Series IQuestion 1100 of 221
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One root of the eq. x2(2+5m)x+3(7+m)=0\displaystyle x^2 - (2 + 5m)x + 3(7 + m) = 0 is reciprocal of the other. Find the value of m\displaystyle m.

Options

A20/3\displaystyle -20/3
B7\displaystyle 7
C1/7\displaystyle 1/7
D117\displaystyle 117
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Correct Answer

Option a20/3\displaystyle -20/3

All Options:

  • A20/3\displaystyle -20/3
  • B7\displaystyle 7
  • C1/7\displaystyle 1/7
  • D117\displaystyle 117

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Detailed Solution & Explanation

Let the roots of the quadratic equation x2(2+5m)x+3(7+m)=0\displaystyle x^2 - (2 + 5m)x + 3(7 + m) = 0 be α\displaystyle \alpha and 1α\displaystyle \frac{1}{\alpha}, as one root is the reciprocal of the other.

The product of the roots of a quadratic equation Ax2+Bx+C=0\displaystyle Ax^2 + Bx + C = 0 is given by C/A\displaystyle C/A.
Here, A=1\displaystyle A = 1 and C=3(7+m)\displaystyle C = 3(7 + m).

The product of the roots is:
α1α=1\alpha \cdot \frac{1}{\alpha} = 1
Applying the product formula:
3(7+m)1=1\frac{3(7 + m)}{1} = 1
3(7+m)=13(7 + m) = 1
21+3m=121 + 3m = 1
3m=203m = -20
m=203m = -\frac{20}{3}

Hence, the correct option is **Option (a)**.

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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