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If a, b, c are real if ax^(2)+ bx + c = ...

If a, b, c are real if `ax^(2)+ bx + c = 0` has two real roots `alpha, beta` where `a lt -1, beta gt 1` then

A

`1+ (c) /(a)+ |(b)/(a)| lt 0`

B

`1- (c) /(a)+ |(b)/(a)| lt 0`

C

c=0

D

`(c) /(a)+ |(b)/(a)| -1 gt 0`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to analyze the given quadratic equation \( ax^2 + bx + c = 0 \) under the conditions provided. Let's break down the solution step by step. ### Step 1: Understanding the Quadratic Function The quadratic function is given as: \[ f(x) = ax^2 + bx + c \] where \( a, b, c \) are real numbers. The roots of this function are denoted as \( \alpha \) and \( \beta \). ### Step 2: Conditions on the Roots We know from the problem statement that: - \( \alpha < -1 \) - \( \beta > 1 \) ### Step 3: Nature of the Parabola Since \( a < -1 \), the parabola opens downwards (because \( a < 0 \)). This means that the vertex of the parabola is a maximum point. ### Step 4: Evaluating the Function at Specific Points We will evaluate the function at \( x = -1 \) and \( x = 1 \): 1. **At \( x = -1 \)**: \[ f(-1) = a(-1)^2 + b(-1) + c = a - b + c \] 2. **At \( x = 1 \)**: \[ f(1) = a(1)^2 + b(1) + c = a + b + c \] ### Step 5: Conditions on the Function Values Since \( \alpha < -1 \) and \( \beta > 1 \), it implies: - The function must be positive between the roots, meaning \( f(-1) < 0 \) and \( f(1) < 0 \). Thus, we have: 1. \( a - b + c < 0 \) 2. \( a + b + c < 0 \) ### Step 6: Combining the Inequalities From the inequalities: 1. \( a - b + c < 0 \) 2. \( a + b + c < 0 \) We can manipulate these inequalities to find conditions on \( b \) and \( c \): - From the first inequality, rearranging gives: \[ c < b - a \] - From the second inequality, rearranging gives: \[ c < -a - b \] ### Step 7: Conclusion The conditions derived suggest that \( c \) must be less than both \( b - a \) and \( -a - b \). This indicates that the value of \( c \) is constrained by the values of \( a \) and \( b \). ### Final Answer The correct option based on the analysis is: - \( 1 + \frac{c}{a} + \left| \frac{b}{a} \right| < 0 \)
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