Let $x,$ $y,$ and $z$ be nonnegative real numbers such that $x^2 + 2y^2 + 5z^2 = 22.$  Find the maximum value of
\[xy + xz + yz.\]
Question:
Let $x,$ $y,$ and $z$ be nonnegative real numbers such that $x^2 + 2y^2 + 5z^2 = 22.$  Find the maximum value of
\[xy + xz + yz.\]
Answer:
Let's think step by step.

user
11
Let $x,$ $y,$ and $z$ be nonnegative real numbers such that $x^2 + 2y^2 + 5z^2 = 22.$  Find the maximum value of
\[xy + xz + yz.\]
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