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Let a,b,c be real if ax^(2)+bx+c=0 has t...

Let a,b,c be real if `ax^(2)+bx+c=0` has two real roots `alpha` and `beta` where `a lt -2` and `beta gt2`, then

A

`4+(2b)/a+c/a=0`

B

`4-(2b)/a+c/a=0`

C

`4+(2b)/a-c/alt0`

D

`4-(2b)/a+c/alt0`

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The correct Answer is:
To solve the problem, we need to analyze the quadratic equation \( ax^2 + bx + c = 0 \) given the conditions on its roots \( \alpha \) and \( \beta \). ### Step 1: Understand the conditions on the roots We know that: - \( \alpha < -2 \) - \( \beta > 2 \) This means that the roots of the quadratic equation are positioned such that one root is less than -2 and the other root is greater than 2. ### Step 2: Analyze the quadratic function The quadratic function can be expressed as: \[ f(x) = ax^2 + bx + c \] Since \( a < -2 \), the parabola opens downwards (as \( a \) is negative). ### Step 3: Determine the behavior of the function between the roots Since \( \alpha < -2 \) and \( \beta > 2 \), the function will be negative between the roots. Therefore, for any \( x \) in the interval \( (-2, 2) \), we have: \[ f(x) < 0 \] ### Step 4: Evaluate the function at the endpoints We need to evaluate \( f(-2) \) and \( f(2) \): 1. **At \( x = 2 \)**: \[ f(2) = a(2^2) + b(2) + c = 4a + 2b + c \] Since \( f(x) < 0 \) for \( x \) between the roots, we have: \[ 4a + 2b + c < 0 \] 2. **At \( x = -2 \)**: \[ f(-2) = a(-2^2) + b(-2) + c = 4a - 2b + c \] Similarly, since \( f(x) < 0 \) for \( x \) between the roots, we have: \[ 4a - 2b + c < 0 \] ### Step 5: Analyze the implications of the inequalities We now have two inequalities: 1. \( 4a + 2b + c < 0 \) 2. \( 4a - 2b + c < 0 \) ### Step 6: Solve the inequalities Subtract the second inequality from the first: \[ (4a + 2b + c) - (4a - 2b + c) < 0 \] This simplifies to: \[ 4b < 0 \implies b < 0 \] ### Conclusion From our analysis, we conclude that: - \( a < -2 \) - \( b < 0 \) Thus, the conditions on the coefficients \( a \) and \( b \) are established based on the given conditions of the roots.
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