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Find the equation whose roots are (alpha...

Find the equation whose roots are `(alpha)/(beta) and (beta)/(alpha)`, where `alpha and beta` are the roots of the equation `x^(2)+2x+3=0`.

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To find the equation whose roots are \(\frac{\alpha}{\beta}\) and \(\frac{\beta}{\alpha}\), where \(\alpha\) and \(\beta\) are the roots of the equation \(x^2 + 2x + 3 = 0\), we can follow these steps: ### Step 1: Find the roots \(\alpha\) and \(\beta\) The roots of the quadratic equation \(x^2 + 2x + 3 = 0\) can be found using the quadratic formula: \[ x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \] Here, \(a = 1\), \(b = 2\), and \(c = 3\). Calculating the discriminant: \[ b^2 - 4ac = 2^2 - 4 \cdot 1 \cdot 3 = 4 - 12 = -8 \] Since the discriminant is negative, the roots are complex: \[ x = \frac{-2 \pm \sqrt{-8}}{2 \cdot 1} = \frac{-2 \pm 2i\sqrt{2}}{2} = -1 \pm i\sqrt{2} \] Thus, the roots are: \[ \alpha = -1 + i\sqrt{2}, \quad \beta = -1 - i\sqrt{2} \] ### Step 2: Calculate \(\alpha + \beta\) and \(\alpha \beta\) Using Vieta's formulas: \[ \alpha + \beta = -\frac{b}{a} = -2 \] \[ \alpha \beta = \frac{c}{a} = 3 \] ### Step 3: Find the sum and product of the new roots The new roots are \(\frac{\alpha}{\beta}\) and \(\frac{\beta}{\alpha}\). **Sum of the new roots:** \[ \frac{\alpha}{\beta} + \frac{\beta}{\alpha} = \frac{\alpha^2 + \beta^2}{\alpha \beta} \] Using the identity \(\alpha^2 + \beta^2 = (\alpha + \beta)^2 - 2\alpha\beta\): \[ \alpha^2 + \beta^2 = (-2)^2 - 2 \cdot 3 = 4 - 6 = -2 \] Thus, \[ \frac{\alpha^2 + \beta^2}{\alpha \beta} = \frac{-2}{3} \] **Product of the new roots:** \[ \frac{\alpha}{\beta} \cdot \frac{\beta}{\alpha} = 1 \] ### Step 4: Form the new quadratic equation Using the sum and product of the roots, we can write the quadratic equation: \[ x^2 - \left(\text{sum of roots}\right)x + \text{product of roots} = 0 \] Substituting the values: \[ x^2 - \left(-\frac{2}{3}\right)x + 1 = 0 \] This simplifies to: \[ x^2 + \frac{2}{3}x + 1 = 0 \] To eliminate the fraction, multiply the entire equation by 3: \[ 3x^2 + 2x + 3 = 0 \] ### Final Answer The required quadratic equation is: \[ 3x^2 + 2x + 3 = 0 \]
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Knowledge Check

  • If alpha,beta are roots of the equation 3x^(2)+4x-5=0 , then (alpha)/(beta) and (beta)/(alpha) are roots of the equation

    A
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    B
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    `(1)/(4)`
    B
    `(7)/(4)`
    C
    `(-7)/(4)`
    D
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    A
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    1
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