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If alpha , beta , gamma are the ro...

If ` alpha , beta , gamma ` are the roots of ` x^3 +px^2 +qx +r=0` then find
`( beta + gamma - 3 alpha ) ( gamma + alpha - 3 beta) (alpha + beta - 3 gamma)`

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To solve the problem, we need to find the expression \((\beta + \gamma - 3\alpha)(\gamma + \alpha - 3\beta)(\alpha + \beta - 3\gamma)\) given that \(\alpha\), \(\beta\), and \(\gamma\) are the roots of the polynomial \(x^3 + px^2 + qx + r = 0\). ### Step 1: Use Vieta's Formulas From Vieta's formulas, we know: - The sum of the roots: \(\alpha + \beta + \gamma = -p\) - The sum of the products of the roots taken two at a time: \(\alpha\beta + \beta\gamma + \gamma\alpha = q\) - The product of the roots: \(\alpha\beta\gamma = -r\) ### Step 2: Rewrite the Expression We can rewrite the expression we need to evaluate: \[ (\beta + \gamma - 3\alpha)(\gamma + \alpha - 3\beta)(\alpha + \beta - 3\gamma) \] Using the identity \(\beta + \gamma = -p - \alpha\), we can express each term in the product: 1. \(\beta + \gamma - 3\alpha = -p - \alpha - 3\alpha = -p - 4\alpha\) 2. \(\gamma + \alpha - 3\beta = -p - \beta - 3\beta = -p - 4\beta\) 3. \(\alpha + \beta - 3\gamma = -p - \gamma - 3\gamma = -p - 4\gamma\) ### Step 3: Substitute Back into the Expression Now substituting these back into the expression, we have: \[ (-p - 4\alpha)(-p - 4\beta)(-p - 4\gamma) \] ### Step 4: Factor Out the Negative Sign Factoring out the negative sign, we get: \[ -(p + 4\alpha)(p + 4\beta)(p + 4\gamma) \] ### Step 5: Expand the Product Now we expand the product: \[ = -(p^3 + 4p^2(\alpha + \beta + \gamma) + 16p(\alpha\beta + \beta\gamma + \gamma\alpha) + 64\alpha\beta\gamma) \] ### Step 6: Substitute Values from Vieta's Formulas Substituting the values from Vieta's formulas: - \(\alpha + \beta + \gamma = -p\) - \(\alpha\beta + \beta\gamma + \gamma\alpha = q\) - \(\alpha\beta\gamma = -r\) We have: \[ = -(p^3 + 4p^2(-p) + 16pq + 64(-r)) \] \[ = -(p^3 - 4p^3 + 16pq - 64r) \] \[ = -(-3p^3 + 16pq - 64r) \] \[ = 3p^3 - 16pq + 64r \] ### Final Answer Thus, the required expression evaluates to: \[ \boxed{3p^3 - 16pq + 64r} \]
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