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If alpha,beta,gamma are the roots of the...

If `alpha,beta,gamma` are the roots of the equation `x^3+a_0x^2+a_1x+a_2=0`, then `(1-alpha^2)(1-beta^2)(1-gamma^2)` is eqyal to:

A

`(1-a_1)^2+(a_0-a_2)^2`

B

`(1+a_1)^2-(a_0-a_2)^2`

C

`(1+a_1)^2+(a_0+a_2)^2`

D

none of these

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The correct Answer is:
To find the value of \((1 - \alpha^2)(1 - \beta^2)(1 - \gamma^2)\) given that \(\alpha, \beta, \gamma\) are the roots of the cubic equation \(x^3 + a_0 x^2 + a_1 x + a_2 = 0\), we can follow these steps: ### Step 1: Expand the Expression We start with the expression: \[ (1 - \alpha^2)(1 - \beta^2)(1 - \gamma^2) \] We can expand this using the distributive property: \[ = 1 - (\alpha^2 + \beta^2 + \gamma^2) + (\alpha^2\beta^2 + \beta^2\gamma^2 + \gamma^2\alpha^2) - \alpha^2\beta^2\gamma^2 \] ### Step 2: Use Vieta's Formulas From Vieta's formulas for the roots of the polynomial \(x^3 + a_0 x^2 + a_1 x + a_2 = 0\), we know: - \(\alpha + \beta + \gamma = -a_0\) - \(\alpha\beta + \beta\gamma + \gamma\alpha = a_1\) - \(\alpha\beta\gamma = -a_2\) ### Step 3: Calculate \(\alpha^2 + \beta^2 + \gamma^2\) We can express \(\alpha^2 + \beta^2 + \gamma^2\) in terms of the sums of the roots: \[ \alpha^2 + \beta^2 + \gamma^2 = (\alpha + \beta + \gamma)^2 - 2(\alpha\beta + \beta\gamma + \gamma\alpha) \] Substituting the values from Vieta's: \[ = (-a_0)^2 - 2a_1 = a_0^2 - 2a_1 \] ### Step 4: Calculate \(\alpha^2\beta^2 + \beta^2\gamma^2 + \gamma^2\alpha^2\) This can be expressed as: \[ \alpha^2\beta^2 + \beta^2\gamma^2 + \gamma^2\alpha^2 = (\alpha\beta + \beta\gamma + \gamma\alpha)^2 - 2\alpha\beta\gamma(\alpha + \beta + \gamma) \] Substituting the values: \[ = a_1^2 - 2(-a_2)(-a_0) = a_1^2 - 2a_2a_0 \] ### Step 5: Calculate \(\alpha^2\beta^2\gamma^2\) This is simply: \[ \alpha^2\beta^2\gamma^2 = (\alpha\beta\gamma)^2 = (-a_2)^2 = a_2^2 \] ### Step 6: Substitute Everything Back Now we substitute back into our expanded expression: \[ (1 - \alpha^2)(1 - \beta^2)(1 - \gamma^2) = 1 - (a_0^2 - 2a_1) + (a_1^2 - 2a_2a_0) - a_2^2 \] Simplifying this gives: \[ = 1 - a_0^2 + 2a_1 + a_1^2 - 2a_2a_0 - a_2^2 \] ### Final Expression Thus, the final expression for \((1 - \alpha^2)(1 - \beta^2)(1 - \gamma^2)\) is: \[ 1 - a_0^2 + 2a_1 + a_1^2 - 2a_2a_0 - a_2^2 \]
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