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

If `alpha, beta` are the roots of the quadratic equation `x^2 + bx - c = 0`, the equation whose roots are `b` and `c`, is a. `x^(2)+alpha x- beta=0` b. `x^(2)-[(alpha +beta)+alpha beta]x-alpha beta( alpha+beta)=0` c. `x^(2)+[(alpha + beta)+alpha beta]x+alpha beta(alpha + beta)=0` d. `x^(2)+[(alpha +beta)+alpha beta)]x -alpha beta(alpha +beta)=0`

A

`x^(2)+alpha x- beta-0`

B

`x^(2)-[(alpha +beta)+alpha beta]x-alpha beta( alpha+beta)=0`

C

`x^(2)+[(alpha + beta)+alpha beta]x+alpha beta(alpha + beta)=0`

D

`x^(2)+[(alpha +beta)+alpha beta)]x -alpha beta(alpha +beta)=0`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to find the quadratic equation whose roots are \( b \) and \( c \), given that \( \alpha \) and \( \beta \) are the roots of the quadratic equation \( x^2 + bx - c = 0 \). ### Step-by-step Solution: 1. **Identify the given quadratic equation**: The equation is given as: \[ x^2 + bx - c = 0 \] Here, the roots are \( \alpha \) and \( \beta \). 2. **Use Vieta's Formulas**: According to Vieta's formulas: - The sum of the roots \( \alpha + \beta = -b \) (Equation 1) - The product of the roots \( \alpha \beta = -c \) (Equation 2) 3. **Express \( b \) and \( c \)**: From Equation 1, we can express \( b \) as: \[ b = -(\alpha + \beta) \] From Equation 2, we can express \( c \) as: \[ c = -\alpha \beta \] 4. **Find the sum and product of the new roots \( b \) and \( c \)**: - The sum of the roots \( b + c \): \[ b + c = -(\alpha + \beta) - \alpha \beta \] - The product of the roots \( b \cdot c \): \[ b \cdot c = (-(\alpha + \beta)) \cdot (-\alpha \beta) = \alpha \beta (\alpha + \beta) \] 5. **Form the new quadratic equation**: The general form of a quadratic equation with roots \( r_1 \) and \( r_2 \) is: \[ x^2 - (r_1 + r_2)x + (r_1 \cdot r_2) = 0 \] Substituting \( r_1 = b \) and \( r_2 = c \): \[ x^2 - (b + c)x + (b \cdot c) = 0 \] Substituting the values we found: \[ x^2 + \left( -(\alpha + \beta) - \alpha \beta \right)x + \left( \alpha \beta (\alpha + \beta) \right) = 0 \] This simplifies to: \[ x^2 + \left( \alpha + \beta + \alpha \beta \right)x + \alpha \beta (\alpha + \beta) = 0 \] 6. **Final equation**: The final quadratic equation is: \[ x^2 + \left( \alpha + \beta + \alpha \beta \right)x + \alpha \beta (\alpha + \beta) = 0 \] ### Conclusion: The correct option is: **c. \( x^2 + [(\alpha + \beta) + \alpha \beta]x + \alpha \beta (\alpha + \beta) = 0 \)**
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