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【简答题】
某射手在一次射击中，射中10环，9环，8环，7环的概率分别为0. 22，0.23，0.24，0.25，则这个射手在一次射击中：（1）射中9环或8环的概率为（ ），（2）不够8环的概率为（ ）。
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举一反三
【单选题】函数f(x,y)=4(x−y)−x2−y2f(x,y)=4(x−y)−x2−y2的极值为
A.
f ( 2 , − 2 ) = 8 " role="presentation" style="display: inline-block; line-height: 0; font-size: 19.52px; overflow-wrap: normal; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; margin: 0px; padding: 1px 0px; color: rgb(0, 0, 0); font-family: "Microsoft YaHei"; position: relative;" > f ( 2 , − 2 ) = 8 f(2,−2)=8
B.
f ( − 2 , − 2 ) = 0 " role="presentation" style="display: inline-block; line-height: 0; font-size: 19.52px; overflow-wrap: normal; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; margin: 0px; padding: 1px 0px; color: rgb(0, 0, 0); font-family: "Microsoft YaHei"; position: relative;" > f ( − 2 , − 2 ) = 0 f(−2,−2)=0
C.
f ( 2 , 2 ) = 0 " role="presentation" style="display: inline-block; line-height: 0; font-size: 19.52px; overflow-wrap: normal; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; margin: 0px; padding: 1px 0px; color: rgb(0, 0, 0); font-family: "Microsoft YaHei"; position: relative;" > f ( 2 , 2 ) = 0 f(2,2)=0
D.
f ( − 2 , 2 ) = 8 " role="presentation" style="display: inline-block; line-height: 0; font-size: 19.52px; overflow-wrap: normal; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; margin: 0px; padding: 1px 0px; color: rgb(0, 0, 0); font-family: "Microsoft YaHei"; position: relative;" > f ( − 2 , 2 ) = 8 f(−2,2)=8
【单选题】(2009年) 设z=f(x2一y2)，则dz等于( )。
A.
2x一2y
B.
2xdx一2ydy
C.
f’(x2一y2)dx
D.
2f’(x2一y2)(xdx—ydy)
【单选题】函数f(x,y)=(6x−x2)(4y−y2)f(x,y)=(6x−x2)(4y−y2)的极值为
A.
f ( 3 , 2 ) = 36 " role="presentation" style="display: inline-block; line-height: 0; font-size: 19.52px; overflow-wrap: normal; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; margin: 0px; padding: 1px 0px; color: rgb(0, 0, 0); font-family: "Microsoft YaHei"; position: relative;" > f ( 3 , 2 ) = 36 f(3,2)=36
B.
f ( 3 , 0 ) = 0 " role="presentation" style="display: inline-block; line-height: 0; font-size: 19.52px; overflow-wrap: normal; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; margin: 0px; padding: 1px 0px; color: rgb(0, 0, 0); font-family: "Microsoft YaHei"; position: relative;" > f ( 3 , 0 ) = 0 f(3,0)=0
C.
f ( 0 , 2 ) = 0 " role="presentation" style="display: inline-block; line-height: 0; font-size: 19.52px; overflow-wrap: normal; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; margin: 0px; padding: 1px 0px; color: rgb(0, 0, 0); font-family: "Microsoft YaHei"; position: relative;" > f ( 0 , 2 ) = 0 f(0,2)=0
D.
f ( 3 , 2 ) = 6 " role="presentation" style="display: inline-block; line-height: 0; font-size: 19.52px; overflow-wrap: normal; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; margin: 0px; padding: 1px 0px; color: rgb(0, 0, 0); font-family: "Microsoft YaHei"; position: relative;" > f ( 3 , 2 ) = 6 f(3,2)=6
【单选题】设函数f(x，y)为可微函数，且对任意的x，y都有 ，则使不等式f(x1，y1)＞f(x2，y2)成立的一个充分条件是( )．
A.
x1＞x2，y1＜y2
B.
x1＞x2，y1＞y2
C.
x1＜x2，y1＜y2
D.
x1＜x2，y1＞y2
【简答题】已知函数f（x）=（x 2 ﹣a）e x ． （1）若a=3，求f（x）的单调区间和极值； （2）若x 1 ，x 2 为f（x）的两个不同的极值点，且 ， 若 恒成立，求实数b的取值范围．
【简答题】盖印可见图层
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