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If a,b,c are three distinct positive rea...

If a,b,c are three distinct positive real numbers which are in H.P., then `(3a + 2b)/(2a - b) + (3c + 2b)/(2c - b)` is

A

Greater than or equal to 10

B

Less than or equal to 10

C

Only equal to 10

D

None of these

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The correct Answer is:
To solve the problem, we need to analyze the expression given that \( a, b, c \) are three distinct positive real numbers in Harmonic Progression (H.P.). ### Step-by-step Solution: 1. **Understanding H.P.**: If \( a, b, c \) are in H.P., then the reciprocals \( \frac{1}{a}, \frac{1}{b}, \frac{1}{c} \) are in Arithmetic Progression (A.P.). This means: \[ \frac{1}{b} = \frac{\frac{1}{a} + \frac{1}{c}}{2} \implies b = \frac{2ac}{a+c} \] 2. **Substituting \( b \)**: We substitute \( b \) in the expression: \[ \frac{3a + 2b}{2a - b} + \frac{3c + 2b}{2c - b} \] becomes: \[ \frac{3a + 2\left(\frac{2ac}{a+c}\right)}{2a - \frac{2ac}{a+c}} + \frac{3c + 2\left(\frac{2ac}{a+c}\right)}{2c - \frac{2ac}{a+c}} \] 3. **Simplifying the First Fraction**: The first term simplifies as follows: \[ \frac{3a + \frac{4ac}{a+c}}{2a - \frac{2ac}{a+c}} = \frac{(3a(a+c) + 4ac)}{(2a(a+c) - 2ac)} = \frac{3a^2 + 3ac + 4ac}{2a^2 + 2ac - 2ac} = \frac{3a^2 + 7ac}{2a^2} \] 4. **Simplifying the Second Fraction**: The second term simplifies similarly: \[ \frac{3c + \frac{4ac}{a+c}}{2c - \frac{2ac}{a+c}} = \frac{(3c(a+c) + 4ac)}{(2c(a+c) - 2ac)} = \frac{3c^2 + 7ac}{2c^2} \] 5. **Combining the Two Fractions**: Now we combine both fractions: \[ \frac{3a^2 + 7ac}{2a^2} + \frac{3c^2 + 7ac}{2c^2} \] Finding a common denominator gives: \[ \frac{(3a^2 + 7ac)c^2 + (3c^2 + 7ac)a^2}{2a^2c^2} \] 6. **Expanding the Numerator**: Expanding the numerator: \[ 3a^2c^2 + 7ac^3 + 3c^2a^2 + 7a^2c = 6a^2c^2 + 7ac(a + c) \] 7. **Final Expression**: Thus, we have: \[ \frac{6a^2c^2 + 7ac(a+c)}{2a^2c^2} \] 8. **Conclusion**: The final expression simplifies to: \[ 3 + \frac{7(a+c)}{2ac} \] ### Final Result: The expression evaluates to: \[ \frac{(3a + 2b)}{(2a - b)} + \frac{(3c + 2b)}{(2c - b)} = 3 + \frac{7(a+c)}{2ac} \]
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