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The expression ax^2+2bx+c, where 'a' is ...

The expression `ax^2+2bx+c`, where 'a' is non-zero real number, has same sign as that of 'a' for every real value of x,then roots of quadratic equation `ax^2+ (b-c) x-2b-c -a-0` are: (a) real and equal (b) real and unequal (c) non-real having positive real part(d) non-real having negative real part

A

ral and equal

B

real and unequal

C

non-real having positive ral part

D

non-real having negative real part

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The correct Answer is:
To solve the problem, we need to analyze the given quadratic expression and the quadratic equation to determine the nature of its roots. ### Step-by-Step Solution: 1. **Understanding the Given Expression**: We have the expression \( ax^2 + 2bx + c \) which has the same sign as \( a \) for every real value of \( x \). This implies that the quadratic does not cross the x-axis, meaning it has no real roots. 2. **Discriminant Analysis**: For a quadratic equation \( ax^2 + bx + c \), the discriminant \( D \) is given by: \[ D = b^2 - 4ac \] Since the expression \( ax^2 + 2bx + c \) has the same sign as \( a \), it means: \[ D < 0 \implies (2b)^2 - 4ac < 0 \implies 4b^2 < 4ac \implies b^2 < ac \] 3. **Analyzing the Given Quadratic Equation**: We need to analyze the quadratic equation: \[ ax^2 + (b - c)x - (2b + c + a) = 0 \] Let's denote the coefficients as follows: - \( A = a \) - \( B = b - c \) - \( C = -(2b + c + a) \) 4. **Calculating the Discriminant of the New Equation**: The discriminant \( D' \) of the new quadratic equation is: \[ D' = (b - c)^2 - 4a(-2b - c - a) \] Simplifying this: \[ D' = (b - c)^2 + 4a(2b + c + a) \] 5. **Expanding and Simplifying**: Expanding \( D' \): \[ D' = (b - c)^2 + 8ab + 4ac + 4a^2 \] We know from earlier that \( 4ac > 4b^2 \), which implies \( 4ac - 4b^2 > 0 \). Thus: \[ D' > 0 \text{ (since all terms are positive)} \] 6. **Conclusion about the Roots**: Since \( D' > 0 \), the quadratic equation \( ax^2 + (b - c)x - (2b + c + a) = 0 \) has real and unequal roots. ### Final Answer: The roots of the quadratic equation are **(b) real and unequal**.
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