MHB What Is the Maximum Value of \(a^2+ab+2b^2\) Given \(a^2-ab+2b^2=8\)?

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The problem involves maximizing the expression \(a^2 + ab + 2b^2\) under the constraint \(a^2 - ab + 2b^2 = 8\) with \(a\) and \(b\) as positive real numbers. Participants discuss various methods to approach the maximization, including substitution and optimization techniques. One user successfully finds the maximum value and is encouraged to share their solution process for clarity and learning. The discussion emphasizes the importance of showing work in mathematical problem-solving.
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$a$ and $b$ are positive real numbers such that $a^2-ab+2b^2=8$.

Find the maximum value of $a^2+ab+2b^2$.
 
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Here:

$\frac{4}{7}(4+\sqrt2)^2$
 
conscipost said:
Here:

$\frac{4}{7}(4+\sqrt2)^2$

Your answer is correct, conscipost! (Yes) Well done!

But I'd appreciate it if you show your solution (but not merely the final answer) so we know what approach you used, sounds good to you?
 
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