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If `0 lt c lt b lt a` and the roots `alpha, beta` the equation `cx^(2)+bx+a=0` are imaginary, then

A

`(|alpha|+|beta|)/(2)=|alpha||beta|`

B

`(1)/(|alpha|)=(1)/(|beta|)`

C

`(1)/(|alpha|)+(1)/(|beta|)lt2`

D

`(1)/(|alpha|)+(1)/(|beta|)gt 2`

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The correct Answer is:
To solve the problem, we need to analyze the conditions given in the question and use the properties of quadratic equations and their roots. ### Step-by-Step Solution: 1. **Understanding the Condition of Imaginary Roots**: For the quadratic equation \( cx^2 + bx + a = 0 \) to have imaginary roots, the discriminant must be less than zero. The discriminant \( D \) is given by: \[ D = b^2 - 4ac \] Therefore, for the roots to be imaginary: \[ b^2 - 4ac < 0 \] 2. **Rearranging the Inequality**: Rearranging the inequality gives us: \[ b^2 < 4ac \] 3. **Using the Given Conditions**: We know from the problem statement that \( 0 < c < b < a \). Since \( c \), \( b \), and \( a \) are all positive, we can use this information to analyze the inequality \( b^2 < 4ac \). 4. **Analyzing the Inequality**: Since \( c < b < a \), we can substitute \( a \) with a value greater than \( b \) and \( c \) with a value less than \( b \). This implies: \[ 4ac > 4bc \quad \text{(since \( a > b \) and \( c < b \))} \] Therefore, we need to check if \( b^2 < 4bc \). 5. **Dividing by \( b \) (since \( b > 0 \))**: Dividing both sides of \( b^2 < 4bc \) by \( b \) gives: \[ b < 4c \] 6. **Conclusion**: We have established that \( b < 4c \) under the conditions provided. Now, we need to analyze the options given in the question to find the correct one. ### Analyzing the Options: 1. **Option 1**: \( \frac{|\alpha| + |\beta|}{2} = |\alpha| + |\beta| \) - This is not possible as it implies both roots are zero. 2. **Option 2**: \( \frac{1}{|\alpha|} = \frac{1}{|\beta|} \) - This implies \( |\alpha| = |\beta| \), which is possible since both roots are conjugates. 3. **Option 3**: \( \frac{1}{|\alpha|} + \frac{1}{|\beta|} < 2 \) - This could be true if both roots are greater than 1. 4. **Option 4**: \( \frac{1}{|\alpha|} + \frac{1}{|\beta|} > 2 \) - This is not possible as it contradicts the condition of the roots being imaginary. ### Final Answer: The correct option is **Option 3**: \( \frac{1}{|\alpha|} + \frac{1}{|\beta|} < 2 \).
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