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If a, b, c are positive real number such...

If a, b, c are positive real number such that `lamba` abc is the minimum value of `a(b^(2)+c^(2))+b(c^(2)+a^(2))+c(a^(2)+b^(2))`, then `lambda`=

A

1

B

2

C

3

D

6

Text Solution

AI Generated Solution

The correct Answer is:
To find the minimum value of the expression \( a(b^2 + c^2) + b(c^2 + a^2) + c(a^2 + b^2) \) and express it in the form \( \lambda abc \), we will use the Arithmetic Mean-Geometric Mean (AM-GM) inequality. ### Step-by-Step Solution: 1. **Identify the Expression**: We need to minimize the expression: \[ S = a(b^2 + c^2) + b(c^2 + a^2) + c(a^2 + b^2) \] 2. **Rearranging the Expression**: We can rewrite \( S \) as: \[ S = ab^2 + ac^2 + bc^2 + ba^2 + ca^2 + cb^2 \] 3. **Applying AM-GM Inequality**: We can apply the AM-GM inequality on the three pairs: - \( ab^2 + ac^2 \) - \( bc^2 + ba^2 \) - \( ca^2 + cb^2 \) According to AM-GM, we have: \[ \frac{ab^2 + ac^2}{2} \geq \sqrt{ab^2 \cdot ac^2} = a \cdot b \cdot c \cdot \sqrt{bc} \] Similarly, we can apply AM-GM to the other pairs. 4. **Combining Results**: By applying AM-GM to all pairs, we get: \[ S \geq 3 \sqrt[3]{(ab^2)(ac^2)(bc^2)(ba^2)(ca^2)(cb^2)} \] The product simplifies to: \[ (abc)^6 \] Hence, we can express the inequality as: \[ S \geq 6abc \] 5. **Finding the Minimum Value**: The minimum value of \( S \) is thus \( 6abc \). 6. **Identifying \( \lambda \)**: We are given that this minimum value can be expressed as \( \lambda abc \). By comparing: \[ \lambda abc = 6abc \] We find that: \[ \lambda = 6 \] ### Conclusion: The value of \( \lambda \) is: \[ \boxed{6} \]

To find the minimum value of the expression \( a(b^2 + c^2) + b(c^2 + a^2) + c(a^2 + b^2) \) and express it in the form \( \lambda abc \), we will use the Arithmetic Mean-Geometric Mean (AM-GM) inequality. ### Step-by-Step Solution: 1. **Identify the Expression**: We need to minimize the expression: \[ S = a(b^2 + c^2) + b(c^2 + a^2) + c(a^2 + b^2) ...
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