已知sinx+siny=1/3,求函数u=sinx—(cosy)^2的最值 u=1/3-siny-(1-siny^2)=siny2-siny-2/3=(siny-1/2)^2-11/12 -1
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已知sinx+siny=1/3,求函数u=sinx—(cosy)^2的最值 u=1/3-siny-(1-siny^2)=siny2-siny-2/3=(siny-1/2)^2-11/12 -1
已知sinx+siny=1/3,求函数u=sinx—(cosy)^2的最值
u=1/3-siny-(1-siny^2)
=siny2-siny-2/3
=(siny-1/2)^2-11/12
-1
已知sinx+siny=1/3,求函数u=sinx—(cosy)^2的最值 u=1/3-siny-(1-siny^2)=siny2-siny-2/3=(siny-1/2)^2-11/12 -1
-1<=sinx<=1
所以-1<=1/3-siny<=1
所以-2/3<=siny<=1
所以siny=-2/3,最大是4/9
u=sinx-cos^2y
u=sinx-(1-sin^2y)
u=1/3-siny-(1-sin^2y)
u=(siny-1/2)^2-11/12
siny=1/3-sinx
因为-1<=-sinx<=1 -2/3<=1/3-sinx<=4/3
所以-2/3<=siny<=4/3
当siny=-2/3时,
u的最大值=...
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u=sinx-cos^2y
u=sinx-(1-sin^2y)
u=1/3-siny-(1-sin^2y)
u=(siny-1/2)^2-11/12
siny=1/3-sinx
因为-1<=-sinx<=1 -2/3<=1/3-sinx<=4/3
所以-2/3<=siny<=4/3
当siny=-2/3时,
u的最大值=(-2/3-1/2)^2-11/12=4/9
这个题目你弄错了siny的取值范围。
最大值是4/9.最小值是-11/12
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