若[tex=0.786x1.286]Ick8WleTp/7hma/4IMmoeA==[/tex]是开集，是否一定有[tex=4.357x1.143]0CVBiUnY7E7QPjWcslRnxBUMsbjyAQGK5ODuEzWFUC8=[/tex]？是否一定有[tex=4.714x1.286]WuMAGtF7A0ONh9CUvCpXLeLIApB8hdSyMg6krPrzniU=[/tex]？

2022-06-03

若[tex=0.786x1.286]Ick8WleTp/7hma/4IMmoeA==[/tex]是开集，是否一定有[tex=4.357x1.143]0CVBiUnY7E7QPjWcslRnxBUMsbjyAQGK5ODuEzWFUC8=[/tex]？是否一定有[tex=4.714x1.286]WuMAGtF7A0ONh9CUvCpXLeLIApB8hdSyMg6krPrzniU=[/tex]？

答案：

解：不一定。任取[tex=4.429x2.357]CKqraPs5CI+MqnTBQyHPYxL0qrEUZRMLhMH0Wey27b0=[/tex]，把[tex=2.286x1.357]ay6tf6ymcaVAoPQIbN6WLA==[/tex]中的所有有理点之集记为[tex=8.071x1.357]fj1oHVXbEEfmURS2A8KyiJtPGd9R0JvkmUvlsWCxWWAdN0nr75b4v6l5oBe4dFFyGNT9qNwJVeC64TloIAG7Lw==[/tex]。对每个[tex=0.714x1.0]MpQqoH/z+LdU3U6gsfTOyQ==[/tex]作开区间[tex=0.714x1.214]yQHqC1grJ00+ooF4d/DRBA==[/tex]，使得[tex=5.071x1.357]aB5RRVvGBNv2sgim1+W5FX055pHRdYDW67Wc3RezUH3BwetSecVZ1GOXLlFx+l7O[/tex]且[tex=3.929x2.143]ycQFk1mONl+Ko/DT19FrmaFcsoVgLpR9uWoBwjcxOpxrjjzo2jCVp3g5IQwQgdOr[/tex]、令[tex=3.714x3.286]vFt7Syx2ycEl2aedQXd4xjwk8OJlRlHykEH6Ns8RGwfy2EqJSsy7T2/FVwGg4iAg[/tex]，则[tex=13.643x2.714]50NpPh0S1XPmjbRRMSDobiEBZIe7o3ecf72cZqzQjD69DNJR6JwyHmqI1b6N9dnQS1eSG0vue6ixrgWJrKbtO4UXbnA5FVG03UFQab2RejLqQ+jzWbf8THxqeNw3vX59GcJoC4Oz0l1uZMnEvJKv8h47FCawZeeaQz1sBDjgh/E=[/tex]。但是，[tex=3.857x1.429]Ab2XICQ0fe9R8Qo3a9hkQTjVuo7EdCjtDIpei5cnSWw=[/tex]，所以[tex=3.214x1.143]COK3A0Mc2dkS6KG0sy1Ug63BAVaxILj0/f721vWWte8=[/tex]，因而[tex=4.929x1.214]187+128ds5rL2c9CC7PQFSQwMKIR1ZwRf1Xc9FdR0wo=[/tex]。取[tex=3.786x1.357]q0zHQm3EjBY/dFvlscmPhQ==[/tex]，则[tex=3.571x1.5]O0yv5NWAQsd/NiSCIzvTNDEB0RCTtDckFWfexLjbxyI=[/tex]，从而[tex=5.429x1.214]NtMoHC4djq2daNm1/SMhaXAHQWrLUVvV87cAkftnyl4=[/tex]

举一反三

内容

0
如图，[tex=3.143x1.286]REaUoNxha/GBn3DE8cgfDA==[/tex]是边长为4的正方形，[tex=0.786x1.286]YggwMQ4w3PxfhkmL0NfgdQ==[/tex]、[tex=0.786x1.286]BlkXDnmzWHxe4M6E9LlofQ==[/tex]分别为[tex=1.571x1.286]cHJ4KDAad01mWuGaiQQpfA==[/tex]、[tex=1.571x1.286]hOo99m7YJCAnVf2cQGX8dQ==[/tex]的中点，则阴影部分的面积为[img=163x138]17e6c55620e728c.png[/img] A: 4 B: 5 C: 6 D: 7 E: 8
1
简述[tex=0.786x1.286]Ick8WleTp/7hma/4IMmoeA==[/tex]蛋白耦联受体信号转导的主要途径。
2
判断下列命题是否为真：（1）[tex=3.643x1.357]/5abqJjwKZ1qr+6hsVFF5EBvfq3ggOFNlHMClz0h9nk=[/tex]（2）[tex=2.929x1.357]rGJpyjIjJpbcoBTWxP0Jiw==[/tex]（3）[tex=4.5x1.357]2wycHMoqU83MyEp17iBils58bR7YLuCTI2G9NVAdlfY=[/tex]（4）[tex=5.214x1.357]CTz2gu+IIm1GgNmYMGaduCRtA41wnW4WqwRWwEhq6aA=[/tex]（5）[tex=4.857x1.357]1DcE2BMMOaZhTuxR/mjgsboXxfg5ET59Dp4I/jjEDuw=[/tex]（6）[tex=4.643x1.357]BSryrsQYOvTP2hTWRu6t4nAuJwlSs4L9jaq70EpB+Us=[/tex]（7）若[tex=6.0x1.357]y0IZLUnBO88nR8WBZYvd7QXv5S1OMINV5cQNzPyiyAc=[/tex]，则[tex=3.429x1.357]1brfPwTkVVIX4GfoMIUskA==[/tex]（8）若[tex=7.643x1.357]MhLfJXZnhbXiB0x3oNtFzThV4Y1mJxe1VYr7PkJE/T6hmTD3WWp+UxbNwvUQ6DHk[/tex]，则[tex=4.143x1.357]LZUA94ISo1po5HWsOVeBCjo0rMvj7uw3bGw5HiZenrI=[/tex]
3
设二维随机变量[tex=2.786x1.286]AG5D6gU/evQZlfwisXgzYw==[/tex]服从区域[tex=0.786x1.286]Ick8WleTp/7hma/4IMmoeA==[/tex]上的均匀分布，其中[tex=0.786x1.286]Ick8WleTp/7hma/4IMmoeA==[/tex]是由[tex=3.143x1.214]ZnUQmzd79zGYITYMpW8zRA==[/tex]，[tex=3.571x1.214]higrHfLYWPZ0zgeKYNbYnQ==[/tex]与[tex=2.357x1.286]+lfyPLkaB2aZzha73p3Bvg==[/tex]所围成的三角形区域。（Ⅰ）求[tex=0.929x1.286]uswT/CEcOIwMpCvTz/zeaA==[/tex]的概率密度[tex=2.5x1.286]uu/ytNPk37vj04MgqWVXSQ==[/tex]；（Ⅱ）求条件概率密度[tex=4.143x1.286]iL1wfpp57oFzxts/g9lJfuh3v+Kw5YMIu2INerlCutw=[/tex]。
4
set1 = {x for x in range(10)} print(set1) 以上代码的运行结果为？ A: {0, 1, 2, 3, 4, 5, 6, 7, 8, 9} B: {0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10} C: {1, 2, 3, 4, 5, 6, 7, 8, 9} D: {1, 2, 3, 4, 5, 6, 7, 8, 9,10}