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Given that x,y,z are positive reals such...

Given that `x,y,z` are positive reals such that `xyz=32` . The minimum value of `x^2+4xy+4y^2+2z^2` is ___________.

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To find the minimum value of the expression \( E = x^2 + 4xy + 4y^2 + 2z^2 \) given that \( xyz = 32 \) and \( x, y, z \) are positive reals, we can apply the AM-GM inequality. ### Step 1: Rewrite the expression We can rewrite the expression \( E \) as: \[ E = x^2 + 4xy + 4y^2 + 2z^2 = x^2 + 2xy + 2xy + 4y^2 + z^2 + z^2 \] This allows us to group terms conveniently for applying AM-GM. ### Step 2: Apply AM-GM inequality By the AM-GM inequality, we have: \[ \frac{x^2 + 2xy + 2xy + 4y^2 + z^2 + z^2}{6} \geq \sqrt[6]{x^2 \cdot (2xy)^2 \cdot 4y^2 \cdot z^2 \cdot z^2} \] Calculating the product: \[ x^2 \cdot (2xy)^2 \cdot 4y^2 \cdot z^2 \cdot z^2 = x^2 \cdot 4x^2y^2 \cdot 4y^2 \cdot z^4 = 16x^4y^4z^4 \] ### Step 3: Substitute \( xyz = 32 \) Since \( xyz = 32 \), we can express \( x^4y^4z^4 \) as: \[ (xyz)^4 = 32^4 = 1048576 \] Thus, we have: \[ E \geq 6 \sqrt[6]{16 \cdot 1048576} \] ### Step 4: Simplify the expression Calculating \( 16 \cdot 1048576 \): \[ 16 \cdot 1048576 = 16777216 \] Now, we need to find the sixth root: \[ \sqrt[6]{16777216} = 16 \] Thus, we have: \[ E \geq 6 \cdot 16 = 96 \] ### Conclusion The minimum value of \( E = x^2 + 4xy + 4y^2 + 2z^2 \) given \( xyz = 32 \) is: \[ \boxed{96} \]

To find the minimum value of the expression \( E = x^2 + 4xy + 4y^2 + 2z^2 \) given that \( xyz = 32 \) and \( x, y, z \) are positive reals, we can apply the AM-GM inequality. ### Step 1: Rewrite the expression We can rewrite the expression \( E \) as: \[ E = x^2 + 4xy + 4y^2 + 2z^2 = x^2 + 2xy + 2xy + 4y^2 + z^2 + z^2 \] This allows us to group terms conveniently for applying AM-GM. ...
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