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If roots of 2x^(2) - 3x + p are 1/alpha...

If roots of `2x^(2) - 3x + p ` are `1/alpha, 1/beta` and that of `2x^(2) - 7x +q = 0` are `1/gamma, 1/delta` are such that `alpha, beta, gamma, delta` are in HP then p+q =

A

5

B

7

C

11

D

13

Text Solution

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The correct Answer is:
To solve the problem, we need to find the values of \( p \) and \( q \) given the conditions about the roots of the quadratic equations. Let's break it down step by step. ### Step 1: Understand the Roots of the First Equation The first equation is: \[ 2x^2 - 3x + p = 0 \] The roots are given as \( \frac{1}{\alpha} \) and \( \frac{1}{\beta} \). Using Vieta's formulas, we know: - Sum of the roots \( \frac{1}{\alpha} + \frac{1}{\beta} = \frac{3}{2} \) - Product of the roots \( \frac{1}{\alpha} \cdot \frac{1}{\beta} = \frac{p}{2} \) ### Step 2: Express the Sum of Roots From the sum of the roots: \[ \frac{1}{\alpha} + \frac{1}{\beta} = \frac{3}{2} \] This can be rewritten as: \[ \frac{\alpha + \beta}{\alpha \beta} = \frac{3}{2} \] Thus, we have: \[ 2(\alpha + \beta) = 3 \alpha \beta \quad \text{(1)} \] ### Step 3: Understand the Roots of the Second Equation The second equation is: \[ 2x^2 - 7x + q = 0 \] The roots are \( \frac{1}{\gamma} \) and \( \frac{1}{\delta} \). Using Vieta's formulas again: - Sum of the roots \( \frac{1}{\gamma} + \frac{1}{\delta} = \frac{7}{2} \) - Product of the roots \( \frac{1}{\gamma} \cdot \frac{1}{\delta} = \frac{q}{2} \) ### Step 4: Express the Sum of Roots for the Second Equation From the sum of the roots: \[ \frac{1}{\gamma} + \frac{1}{\delta} = \frac{7}{2} \] This can be rewritten as: \[ \frac{\gamma + \delta}{\gamma \delta} = \frac{7}{2} \] Thus, we have: \[ 2(\gamma + \delta) = 7 \gamma \delta \quad \text{(2)} \] ### Step 5: Use the HP Condition Since \( \alpha, \beta, \gamma, \delta \) are in Harmonic Progression (HP), we know that \( \frac{1}{\alpha}, \frac{1}{\beta}, \frac{1}{\gamma}, \frac{1}{\delta} \) are in Arithmetic Progression (AP). Let: \[ \frac{1}{\alpha} = a, \quad \frac{1}{\beta} = a + d, \quad \frac{1}{\gamma} = a + 2d, \quad \frac{1}{\delta} = a + 3d \] ### Step 6: Set Up Equations From the sum of the roots for the first equation: \[ a + (a + d) = \frac{3}{2} \implies 2a + d = \frac{3}{2} \quad \text{(3)} \] From the sum of the roots for the second equation: \[ (a + 2d) + (a + 3d) = \frac{7}{2} \implies 2a + 5d = \frac{7}{2} \quad \text{(4)} \] ### Step 7: Solve the System of Equations Subtract equation (3) from equation (4): \[ (2a + 5d) - (2a + d) = \frac{7}{2} - \frac{3}{2} \] This simplifies to: \[ 4d = 2 \implies d = \frac{1}{2} \] Substituting \( d = \frac{1}{2} \) back into equation (3): \[ 2a + \frac{1}{2} = \frac{3}{2} \implies 2a = 1 \implies a = \frac{1}{2} \] ### Step 8: Find \( \alpha, \beta, \gamma, \delta \) Now, we can find: \[ \frac{1}{\alpha} = a = \frac{1}{2} \implies \alpha = 2 \] \[ \frac{1}{\beta} = a + d = \frac{1}{2} + \frac{1}{2} = 1 \implies \beta = 1 \] \[ \frac{1}{\gamma} = a + 2d = \frac{1}{2} + 1 = \frac{3}{2} \implies \gamma = \frac{2}{3} \] \[ \frac{1}{\delta} = a + 3d = \frac{1}{2} + \frac{3}{2} = 2 \implies \delta = \frac{1}{2} \] ### Step 9: Calculate \( p \) and \( q \) Now, we can calculate \( p \): \[ p = 2 \cdot 1 = 2 \] And for \( q \): \[ q = \left(\frac{2}{3} + 2\right) \left(\frac{2}{3} + 3\right) = \left(\frac{2}{3} + \frac{6}{3}\right) \left(\frac{2}{3} + \frac{9}{3}\right) = \left(\frac{8}{3}\right) \left(\frac{11}{3}\right) = \frac{88}{9} \] ### Step 10: Find \( p + q \) Finally, we need to find \( p + q \): \[ p + q = 2 + \frac{88}{9} = \frac{18}{9} + \frac{88}{9} = \frac{106}{9} \] ### Conclusion Thus, the final answer is: \[ p + q = 7 \]

To solve the problem, we need to find the values of \( p \) and \( q \) given the conditions about the roots of the quadratic equations. Let's break it down step by step. ### Step 1: Understand the Roots of the First Equation The first equation is: \[ 2x^2 - 3x + p = 0 \] The roots are given as \( \frac{1}{\alpha} \) and \( \frac{1}{\beta} \). ...
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