设正实数 x，y，z 满足 x2－3xy＋4y2－z＝0 .则当 xyz 取得最大值时， 2x+1y+2z 的最大值为( )_刷题宝

题干

设正实数 x，y，z 满足 x2－3xy＋4y2－z＝0 .则当

x

y

z

取得最大值时，

2

x

+

1

y

+

2

z

的最大值为( )

A：0

B： $\frac{9}{4}$

C：1

D：3

上一题下一题 0.0难度选择题更新时间:2019-04-18 08:17:03

答案(点此获取答案解析）

C

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