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If ax^(2)+bx+c = 0 has no real roots and...

If `ax^(2)+bx+c = 0` has no real roots and a, b, c `in` R such that `a + c gt 0`, then

A

`a - b + c lt 0`

B

`a - b + c gt 0`

C

`a + c = b`

D

all of these

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The correct Answer is:
To solve the problem, we need to analyze the quadratic equation \( ax^2 + bx + c = 0 \) under the conditions that it has no real roots and that \( a + c > 0 \). ### Step-by-Step Solution: 1. **Understanding the Condition for No Real Roots**: A quadratic equation has no real roots if its discriminant is less than zero. The discriminant \( D \) for the equation \( ax^2 + bx + c = 0 \) is given by: \[ D = b^2 - 4ac \] For the equation to have no real roots, we require: \[ D < 0 \implies b^2 - 4ac < 0 \implies b^2 < 4ac \] 2. **Analyzing the Condition \( a + c > 0 \)**: We are given that \( a + c > 0 \). This means that the sum of the coefficients \( a \) and \( c \) is positive. 3. **Relating \( a \), \( b \), and \( c \)**: Since \( b^2 < 4ac \) and \( a + c > 0 \), we can infer that both \( a \) and \( c \) must have the same sign (either both positive or both negative) for their sum to be positive. However, since we are looking for a relation involving \( a \), \( b \), and \( c \), we will consider the case where both \( a \) and \( c \) are positive. 4. **Considering the Function \( f(x) = ax^2 + bx + c \)**: Since \( a > 0 \) (as \( a + c > 0 \) and both \( a \) and \( c \) are positive), the graph of the quadratic opens upwards. Given that there are no real roots, the entire graph lies above the x-axis for all \( x \). 5. **Evaluating \( f(-1) \)**: We can evaluate the function at \( x = -1 \): \[ f(-1) = a(-1)^2 + b(-1) + c = a - b + c \] Since the quadratic function \( f(x) \) is always greater than zero for all \( x \), we have: \[ f(-1) > 0 \implies a - b + c > 0 \] 6. **Conclusion**: Therefore, we conclude that: \[ a - b + c > 0 \] ### Final Answer: The relation between \( a \), \( b \), and \( c \) is: \[ a - b + c > 0 \]

To solve the problem, we need to analyze the quadratic equation \( ax^2 + bx + c = 0 \) under the conditions that it has no real roots and that \( a + c > 0 \). ### Step-by-Step Solution: 1. **Understanding the Condition for No Real Roots**: A quadratic equation has no real roots if its discriminant is less than zero. The discriminant \( D \) for the equation \( ax^2 + bx + c = 0 \) is given by: \[ D = b^2 - 4ac ...
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