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If alpha, beta are the roots of x ^(2) +...

If `alpha, beta` are the roots of `x ^(2) +x + 2 =0 and gamma, delta` are the roots of `x ^(2) + 3x + 4 =0.` then `(alpha + gamma) ( alpha +delta) ( beta + gamma )(beta+delta) ` is equal to

A

`-18`

B

`18`

C

24

D

44

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The correct Answer is:
To solve the problem, we need to find the value of \((\alpha + \gamma)(\alpha + \delta)(\beta + \gamma)(\beta + \delta)\), where \(\alpha, \beta\) are the roots of the equation \(x^2 + x + 2 = 0\) and \(\gamma, \delta\) are the roots of the equation \(x^2 + 3x + 4 = 0\). ### Step 1: Find the roots of the first equation The roots of the equation \(x^2 + x + 2 = 0\) can be calculated using the quadratic formula: \[ x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \] Here, \(a = 1\), \(b = 1\), and \(c = 2\). \[ x = \frac{-1 \pm \sqrt{1^2 - 4 \cdot 1 \cdot 2}}{2 \cdot 1} = \frac{-1 \pm \sqrt{1 - 8}}{2} = \frac{-1 \pm \sqrt{-7}}{2} = \frac{-1 \pm i\sqrt{7}}{2} \] Thus, the roots are: \[ \alpha = \frac{-1 + i\sqrt{7}}{2}, \quad \beta = \frac{-1 - i\sqrt{7}}{2} \] ### Step 2: Find the roots of the second equation Now, we find the roots of the equation \(x^2 + 3x + 4 = 0\) using the same quadratic formula: \[ x = \frac{-3 \pm \sqrt{3^2 - 4 \cdot 1 \cdot 4}}{2 \cdot 1} = \frac{-3 \pm \sqrt{9 - 16}}{2} = \frac{-3 \pm \sqrt{-7}}{2} = \frac{-3 \pm i\sqrt{7}}{2} \] Thus, the roots are: \[ \gamma = \frac{-3 + i\sqrt{7}}{2}, \quad \delta = \frac{-3 - i\sqrt{7}}{2} \] ### Step 3: Calculate \((\alpha + \gamma)(\alpha + \delta)(\beta + \gamma)(\beta + \delta)\) We can express this product as: \[ (\alpha + \gamma)(\alpha + \delta) = \alpha^2 + \alpha(\gamma + \delta) + \gamma\delta \] \[ (\beta + \gamma)(\beta + \delta) = \beta^2 + \beta(\gamma + \delta) + \gamma\delta \] ### Step 4: Find \(\gamma + \delta\) and \(\gamma\delta\) From the second equation \(x^2 + 3x + 4 = 0\): - Sum of roots \(\gamma + \delta = -3\) - Product of roots \(\gamma\delta = 4\) ### Step 5: Substitute values Now substituting these values: \[ (\alpha + \gamma)(\alpha + \delta) = \alpha^2 - 3\alpha + 4 \] \[ (\beta + \gamma)(\beta + \delta) = \beta^2 - 3\beta + 4 \] ### Step 6: Calculate \(\alpha^2\) and \(\beta^2\) Using the first equation \(x^2 + x + 2 = 0\): - \(\alpha^2 = -\alpha - 2\) - \(\beta^2 = -\beta - 2\) ### Step 7: Substitute \(\alpha^2\) and \(\beta^2\) into the expressions Substituting \(\alpha^2\) and \(\beta^2\): \[ (\alpha + \gamma)(\alpha + \delta) = (-\alpha - 2) - 3\alpha + 4 = -4\alpha + 2 \] \[ (\beta + \gamma)(\beta + \delta) = (-\beta - 2) - 3\beta + 4 = -4\beta + 2 \] ### Step 8: Final multiplication Now we multiply: \[ (-4\alpha + 2)(-4\beta + 2) = 16\alpha\beta - 8(\alpha + \beta) + 4 \] Using \(\alpha\beta = 2\) and \(\alpha + \beta = -1\): \[ = 16(2) - 8(-1) + 4 = 32 + 8 + 4 = 44 \] ### Final Answer Thus, the value of \((\alpha + \gamma)(\alpha + \delta)(\beta + \gamma)(\beta + \delta)\) is: \[ \boxed{44} \]
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