• 2022-06-11
    When a vector field satisfies ( ), it can be expressed by the gradient of a scalar field.
    A: [img=95x37]1803b96a67f7f7c.png[/img]
    B: [img=87x36]1803b96a6fd7092.png[/img]
    C: [img=129x51]1803b96a77abc30.png[/img]
    D: [img=100x42]1803b96a7efa2a8.png[/img]
  • D

    内容

    • 0

      7、二次函数[img=120x26]18031ef2ad3cc4e.png[/img]的对称轴x=2,则f(3)<f(2).

    • 1

      令F(x):x是有理数,G(x):x是实数。将命题“所有的有理数都是实数,但有的有实数不是有理数”符号化为() 未知类型:{'options': ['17e0a83a4157352.jpgx(F(x)∧G(x))∧[img=8x14]17e0a83a35505d4.jpg[/img]x(G(x)[img=14x9]17e0a73094b5dcf.jpg[/img][img=10x11]17e0a839b915354.jpg[/img]F(x))', ' [img=8x14]17e0a83a4157352.jpg[/img]x(F(x)[img=14x9]17e0a73094b5dcf.jpg[/img]G(x))∧[img=8x14]17e0a83a35505d4.jpg[/img]x(G(x)∧[img=10x11]17e0a839b915354.jpg[/img]F(x))', ' [img=8x14]17e0a83a4157352.jpg[/img]x(F(x)∧G(x))∧[img=8x14]17e0a83a35505d4.jpg[/img]x(G(x)∧[img=10x11]17e0a839b915354.jpg[/img]F(x))', ' [img=8x14]17e0a83a4157352.jpg[/img]x(F(x)[img=14x9]17e0a73094b5dcf.jpg[/img]G(x))∧[img=8x14]17e0a83a35505d4.jpg[/img]x(G(x)[img=14x9]17e0a73094b5dcf.jpg[/img][img=10x11]17e0a839b915354.jpg[/img]F(x))'], 'type': 102}

    • 2

      在下列命题中:如果f(x)=[img=28x44]17e0bf9914bb2f1.png[/img],那么[img=27x29]17e0bf97582597b.png[/img]f(x)=0;如果f(x)=[img=28x44]17e0bf992111a1c.png[/img],那么[img=27x29]17e0bf97582597b.png[/img]f(x)=0;如果f(x)=[img=55x44]17e0bf992d8de0a.png[/img],那么[img=29x29]17e0bf9939482bb.png[/img]f(x)不存在;如果f(x)=[img=87x53]17e0bf99450fa82.png[/img],那么[img=27x29]17e0bf97582597b.png[/img]f(x)=0。其中错误命题的个数是( A: 0 B: 1 C: 2 D: 3

    • 3

      u is any scalar field, the curl of [img=36x19]1803a2a03d38f79.png[/img] is A: 0 B: [img=95x28]1803a2a04565cdd.png[/img] C: x \vec{i} +y \vec{j}+z \vec{k}[img=95x28]1803a2a04da7289.png[/img] D: [img=117x28]1803a2a0564b28b.png[/img]

    • 4

      X~N(1,1), 密度函数为[img=37x25]18038fe689205b5.png[/img], 分布函数为F(x), 则( ) A: [img=198x25]18038fe690a03ee.png[/img] B: [img=101x25]18038fe69af96aa.png[/img] C: [img=67x25]18038fe6a3b8e5b.png[/img][img=118x25]18038fe6ab93d6f.png[/img] D: F(x)=F(-x)