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If alpha, beta are the roots of ax^(2)+b...

If `alpha, beta` are the roots of `ax^(2)+bx+c=0`, `alpha beta=3` and a, b, c are in A.P., then `alpha+beta` =

A

-4

B

-1

C

4

D

-2

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we will follow these steps: ### Step 1: Understand the given information We know that \( \alpha \) and \( \beta \) are the roots of the quadratic equation \( ax^2 + bx + c = 0 \). We are given: - \( \alpha \beta = 3 \) - \( a, b, c \) are in Arithmetic Progression (A.P.) ### Step 2: Use Vieta's Formulas From Vieta's formulas, we know: - The sum of the roots \( \alpha + \beta = -\frac{b}{a} \) - The product of the roots \( \alpha \beta = \frac{c}{a} \) Since we are given \( \alpha \beta = 3 \), we can write: \[ \frac{c}{a} = 3 \implies c = 3a \] ### Step 3: Apply the A.P. condition Since \( a, b, c \) are in A.P., we can express this condition as: \[ b = \frac{a + c}{2} \] Substituting \( c = 3a \) into the A.P. condition gives: \[ b = \frac{a + 3a}{2} = \frac{4a}{2} = 2a \] ### Step 4: Find \( \alpha + \beta \) Now, substituting \( b = 2a \) into the formula for the sum of the roots: \[ \alpha + \beta = -\frac{b}{a} = -\frac{2a}{a} = -2 \] ### Conclusion Thus, the value of \( \alpha + \beta \) is: \[ \alpha + \beta = -2 \] ### Final Answer The answer is \( -2 \). ---
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