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If the equation ax^(2)+bx+c=0 (a gt 0) h...

If the equation `ax^(2)+bx+c=0 (a gt 0)` has two roots `alpha and beta` such that `alpha lt -2 and beta gt 2`, then

A

`b^(2) -4ac gt 0`

B

`4a+2 |b| +c lt 0`

C

`a+|b| +c lt 0`

D

`c lt 0`

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The correct Answer is:
To solve the problem, we need to analyze the quadratic equation given by \( ax^2 + bx + c = 0 \) where \( a > 0 \). The roots of this equation are denoted as \( \alpha \) and \( \beta \) with the conditions \( \alpha < -2 \) and \( \beta > 2 \). ### Step-by-Step Solution: 1. **Understanding the Roots**: - The roots \( \alpha \) and \( \beta \) are the solutions to the quadratic equation. Given that \( \alpha < -2 \) and \( \beta > 2 \), we can infer that the graph of the quadratic function opens upwards (since \( a > 0 \)) and crosses the x-axis at two points, one to the left of -2 and one to the right of 2. 2. **Using Vieta's Formulas**: - According to Vieta's formulas, for the quadratic equation \( ax^2 + bx + c = 0 \): - The sum of the roots \( \alpha + \beta = -\frac{b}{a} \) - The product of the roots \( \alpha \beta = \frac{c}{a} \) 3. **Analyzing the Sum of Roots**: - Since \( \alpha < -2 \) and \( \beta > 2 \), we can express the sum: \[ \alpha + \beta < -2 + 2 = 0 \] - Therefore, we have \( -\frac{b}{a} < 0 \), which implies that \( b > 0 \). 4. **Analyzing the Product of Roots**: - The product of the roots can be analyzed as follows: \[ \alpha \beta < (-2)(2) = -4 \] - Thus, \( \frac{c}{a} < -4 \) which leads to \( c < -4a \) (since \( a > 0 \)). 5. **Conclusion**: - From the analysis, we conclude that: - \( b > 0 \) - \( c < -4a \) ### Final Result: The conditions on the coefficients of the quadratic equation \( ax^2 + bx + c = 0 \) are: - \( b > 0 \) - \( c < -4a \)
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ML KHANNA-THEORY OF QUADRATIC EQUATIONS -Problem Set - 2
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