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If α,β\displaystyle \alpha, \beta are the roots of equation x2+7x+12=0\displaystyle x^2 + 7x + 12 = 0 then the equation whose roots (α+β)2\displaystyle (\alpha + \beta)^2 and (αβ)2\displaystyle (\alpha - \beta)^2 will be

Options

Ax214x+49=0\displaystyle x^2 - 14x + 49 = 0
Bx224x+144=0\displaystyle x^2 - 24x + 144 = 0
Cx250x+49=0\displaystyle x^2 - 50x + 49 = 0
Dx219x+49=0\displaystyle x^2 - 19x + 49 = 0
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Correct Answer

Option cx250x+49=0\displaystyle x^2 - 50x + 49 = 0

All Options:

  • Ax214x+49=0\displaystyle x^2 - 14x + 49 = 0
  • Bx224x+144=0\displaystyle x^2 - 24x + 144 = 0
  • Cx250x+49=0\displaystyle x^2 - 50x + 49 = 0
  • Dx219x+49=0\displaystyle x^2 - 19x + 49 = 0

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Detailed Solution & Explanation

Given the equation:
x2+7x+12=0x^2 + 7x + 12 = 0
We factor the quadratic expression to find the roots α\displaystyle \alpha and β\displaystyle \beta:
x2+3x+4x+12=0    (x+3)(x+4)=0    α=3,β=4x^2 + 3x + 4x + 12 = 0 \implies (x+3)(x+4) = 0 \implies \alpha = -3, \beta = -4
Now we find the roots of the new equation, which are (α+β)2\displaystyle (\alpha + \beta)^2 and (αβ)2\displaystyle (\alpha - \beta)^2:
1. **First root:**
(α+β)2=(34)2=(7)2=49(\alpha + \beta)^2 = (-3 - 4)^2 = (-7)^2 = 49
2. **Second root:**
(αβ)2=(3(4))2=(1)2=1(\alpha - \beta)^2 = (-3 - (-4))^2 = (1)^2 = 1
The roots of the new quadratic equation are 49\displaystyle 49 and 1\displaystyle 1.
Calculating the sum (S\displaystyle S') and product (P\displaystyle P') of these new roots:
S=49+1=50S' = 49 + 1 = 50
P=49×1=49P' = 49 \times 1 = 49
The required quadratic equation is:
x2Sx+P=0    x250x+49=0x^2 - S'x + P' = 0 \implies x^2 - 50x + 49 = 0
This matches 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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