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For all positive values of x and y, the ...

For all positive values of x and y, the value of
`((1+x+x^(2))(1+y+y^(2)))/(xy)`,is

A

`le9`

B

`lt9`

C

`ge9`

D

`gt9`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to evaluate the expression \[ \frac{(1 + x + x^2)(1 + y + y^2)}{xy} \] for all positive values of \(x\) and \(y\). ### Step 1: Simplify the expression We can rewrite the expression as: \[ \frac{(1 + x + x^2)}{x} \cdot \frac{(1 + y + y^2)}{y} \] This gives us two separate functions: \[ f(x) = \frac{1 + x + x^2}{x} \quad \text{and} \quad g(y) = \frac{1 + y + y^2}{y} \] ### Step 2: Analyze \(f(x)\) Now, let's analyze \(f(x)\): \[ f(x) = \frac{1}{x} + 1 + x \] ### Step 3: Apply the AM-GM Inequality Using the Arithmetic Mean-Geometric Mean (AM-GM) inequality on the terms \(x\) and \(\frac{1}{x}\): \[ \frac{x + \frac{1}{x}}{2} \geq \sqrt{x \cdot \frac{1}{x}} = 1 \] This implies: \[ x + \frac{1}{x} \geq 2 \] Adding 1 to both sides gives: \[ f(x) = \frac{1}{x} + 1 + x \geq 2 + 1 = 3 \] ### Step 4: Analyze \(g(y)\) Similarly, we can analyze \(g(y)\): \[ g(y) = \frac{1 + y + y^2}{y} = \frac{1}{y} + 1 + y \] Applying the same AM-GM inequality: \[ \frac{y + \frac{1}{y}}{2} \geq 1 \implies y + \frac{1}{y} \geq 2 \] Thus, we have: \[ g(y) \geq 3 \] ### Step 5: Combine the results Now, we can combine the results of \(f(x)\) and \(g(y)\): \[ \frac{(1 + x + x^2)(1 + y + y^2)}{xy} = f(x) \cdot g(y) \geq 3 \cdot 3 = 9 \] ### Conclusion Therefore, we conclude that: \[ \frac{(1 + x + x^2)(1 + y + y^2)}{xy} \geq 9 \] ### Final Answer The value of the expression for all positive values of \(x\) and \(y\) is: \[ \boxed{9} \]

To solve the problem, we need to evaluate the expression \[ \frac{(1 + x + x^2)(1 + y + y^2)}{xy} \] for all positive values of \(x\) and \(y\). ...
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