If x > 0, the maximum value of y = 4-2x-x is 0

y=4-(2x+1/x)
Because x is greater than 0
There is an average inequality
Y ≤ 4-2 radical 2
The equal sign is obtained when 2x = 1 / X
That is, x = root (1 / 2)
To get the maximum value (4-2 root 2)

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