EquationsMCQMTP March 21Question 1077 of 221
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If arithmetic mean between roots of a quadratic equation is 8\displaystyle 8 and the geometric mean between them is 5\displaystyle 5, the equation is

Options

Ax216x25=0\displaystyle x^2 - 16x - 25 = 0
Bx216x+25=0\displaystyle x^2 - 16x + 25 = 0
Cx2+16x+25=0\displaystyle x^2 + 16x + 25 = 0
DNone of these
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Correct Answer

Option bx216x+25=0\displaystyle x^2 - 16x + 25 = 0

All Options:

  • Ax216x25=0\displaystyle x^2 - 16x - 25 = 0
  • Bx216x+25=0\displaystyle x^2 - 16x + 25 = 0
  • Cx2+16x+25=0\displaystyle x^2 + 16x + 25 = 0
  • DNone of these

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Detailed Solution & Explanation

Let the roots of the quadratic equation be α\displaystyle \alpha and β\displaystyle \beta.
We are given:
1. **Arithmetic Mean (AM) between roots is 8:**
α+β2=8    α+β=16\frac{\alpha + \beta}{2} = 8 \implies \alpha + \beta = 16
Thus, the sum of roots (S\displaystyle S) is 16\displaystyle 16.
2. **Geometric Mean (GM) between roots is 5:**
αβ=5    αβ=25\sqrt{\alpha\beta} = 5 \implies \alpha\beta = 25
Thus, the product of roots (P\displaystyle P) is 25\displaystyle 25.

The general form of a quadratic equation is:
x2Sx+P=0x^2 - Sx + P = 0
Substitute the sum (S=16\displaystyle S = 16) and product (P=25\displaystyle P = 25):
x216x+25=0x^2 - 16x + 25 = 0
This corresponds to Option b.

**Option b**

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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