EquationsMCQMTP Dec 22 - Series 1Question 1091 of 221
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If one root is 5z2+13z+y=0\displaystyle 5z^2 + 13z + y = 0 is reciprocal of the other, then the value of y\displaystyle y is

Options

A5\displaystyle 5
B13\displaystyle 13
C1/5\displaystyle 1/5
D13\displaystyle -13
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Correct Answer

Option a5\displaystyle 5

All Options:

  • A5\displaystyle 5
  • B13\displaystyle 13
  • C1/5\displaystyle 1/5
  • D13\displaystyle -13

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Detailed Solution & Explanation

Given equation (correcting the standard typo "If one root is 5z2...\displaystyle 5z^2..." to "If one root of the equation 5z2+13z+y=0\displaystyle 5z^2 + 13z + y = 0 is reciprocal of the other"):
5z2+13z+y=05z^2 + 13z + y = 0
Let the roots be α\displaystyle \alpha and β\displaystyle \beta. Since one root is the reciprocal of the other, we have:
β=1α    αβ=1\beta = \frac{1}{\alpha} \implies \alpha\beta = 1
From Vieta's formulas, the product of roots is c/a=y/5\displaystyle c/a = y/5:
αβ=y5\alpha\beta = \frac{y}{5}
Equating both expressions for the product of roots:
y5=1    y=5\frac{y}{5} = 1 \implies y = 5
This corresponds to Option a.

**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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