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If a, b, c are in geometric progresion a...

If `a`, `b`, `c` are in geometric progresion and the roots of the equations `ax^(2)+2bx+c=0` are `alpha` and `beta` and those of `cx^(2)+2bx+a=0` are `gamma` and `delta` then

A

`alpha ne beta ne gamma ne delta`

B

`alpha ne beta` and `gamma ne delta`

C

`a alpha = a beta = c gamma = c delta`

D

`alpha=beta` , `gamma ne delta`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we will analyze the given equations and the conditions provided. ### Step 1: Understand the given conditions We know that \( a, b, c \) are in geometric progression. This means that: \[ \frac{b^2}{ac} = 1 \quad \text{(1)} \] ### Step 2: Analyze the roots of the first equation The first equation is: \[ ax^2 + 2bx + c = 0 \] Let the roots of this equation be \( \alpha \) and \( \beta \). By Vieta's formulas, we have: \[ \alpha + \beta = -\frac{2b}{a} \quad \text{(2)} \] \[ \alpha \beta = \frac{c}{a} \quad \text{(3)} \] ### Step 3: Analyze the roots of the second equation The second equation is: \[ cx^2 + 2bx + a = 0 \] Let the roots of this equation be \( \gamma \) and \( \delta \). Again, by Vieta's formulas, we have: \[ \gamma + \delta = -\frac{2b}{c} \quad \text{(4)} \] \[ \gamma \delta = \frac{a}{c} \quad \text{(5)} \] ### Step 4: Relate the roots of both equations Since \( a, b, c \) are in geometric progression, we can express \( b \) in terms of \( a \) and \( c \): \[ b = \sqrt{ac} \quad \text{(6)} \] ### Step 5: Substitute \( b \) into the equations Substituting equation (6) into equations (2) and (4): From (2): \[ \alpha + \beta = -\frac{2\sqrt{ac}}{a} = -\frac{2\sqrt{c}}{\sqrt{a}} \quad \text{(7)} \] From (4): \[ \gamma + \delta = -\frac{2\sqrt{ac}}{c} = -\frac{2\sqrt{a}}{\sqrt{c}} \quad \text{(8)} \] ### Step 6: Analyze the product of the roots From equations (3) and (5): Using (3): \[ \alpha \beta = \frac{c}{a} \quad \text{(9)} \] Using (5): \[ \gamma \delta = \frac{a}{c} \quad \text{(10)} \] ### Step 7: Establish relationships between roots From the properties of the equations, we can establish that: - The roots of the second equation are the reciprocals of the roots of the first equation, i.e., \( \gamma = \frac{1}{\alpha} \) and \( \delta = \frac{1}{\beta} \). ### Step 8: Conclusion Since \( \alpha \) and \( \beta \) are roots of the first equation and \( \gamma \) and \( \delta \) are their reciprocals, we can conclude: \[ \alpha \beta = \frac{c}{a}, \quad \gamma \delta = \frac{a}{c} \] This implies: \[ \alpha = \beta \quad \text{and} \quad \gamma = \delta \quad \text{(since they are reciprocals)} \] Thus, the correct answer is: **Option C: \( \alpha = \beta \) and \( \gamma = \delta \)**.

To solve the problem, we will analyze the given equations and the conditions provided. ### Step 1: Understand the given conditions We know that \( a, b, c \) are in geometric progression. This means that: \[ \frac{b^2}{ac} = 1 \quad \text{(1)} \] ...
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