若向量[img=27x29]1803bbf1e1cd681.png[/img],且向量[img=115x29]1803bbf1e945ae2.png[/img],[img=35x24]1803bbf1f13de8a.png[/img]= - 18,则[img=29x19]1803bbf1fc71fcd.png[/img]( )
A: (4,-2,-4)
B: (-4,-2,-4)
C: (-4,2,4)
D: (4,-2,4)
A: (4,-2,-4)
B: (-4,-2,-4)
C: (-4,2,4)
D: (4,-2,4)
C
举一反三
- 若向量[img=27x29]1803bbf0a3a1732.png[/img],且向量[img=115x29]1803bbf0ab97983.png[/img],[img=35x24]1803bbf0b543bb7.png[/img]= - 18,则[img=29x19]1803bbf0bd455ca.png[/img]( ) A: (4,-2,-4) B: (-4,-2,-4) C: (-4,2,4) D: (4,-2,4)
- 求不定积分[img=112x35]17da6538063a9e4.png[/img]; ( ) A: (x^4*log(x)^2)/4 + (x^4*(log(x) - 1/4))/ B: (x^4*log(x)^2)/4 - (x^4*(log(x) - 1/4))/8 C: (x^4*log(x)^2)/4 - (x^4*(log(x) - 1/4)) D: (x^4*log(x)^2)/4 + (x^4*(log(x) - 1/4))/8
- 求函数[img=173x42]17da65390bf2806.png[/img]的导数; ( ) A: tan(pi/4 + x/2) B: (tan(pi/4 + x/2)^2/2 ) /tan(pi/4 ) C: (tan(pi/4 + x/2)^2/2 + 1/2) D: (tan(pi/4 + x/2)^2/2 + 1/2) /tan(pi/4 + x/2)
- 随机变量X的概率密度为[img=239x61]1803915d900b3cb.png[/img]则常数c为 A: 2 B: [img=98x52]1803915d9894210.png[/img] C: 1 D: 3 E: 4 F: 1/2 G: 1/3 H: 1/4
- 随机变量X的概率密度为[img=239x61]1802d3e895f944e.png[/img]则常数c为 A: 2 B: [img=98x52]1802d3e89f1fea8.png[/img] C: 1 D: 3 E: 4 F: 1/2 G: 1/3 H: 1/4
内容
- 0
设随机变量X有概率密度[img=180x49]17e441f3ba0a6ad.png[/img] ,已知X的分布函数F(1)=1/4,则有 A: a=1/2,b=0 B: a=0,b=1/2 C: a=1,b=1/2 D: a=1/4,b=1/4
- 1
下列碳正离子稳定性顺序应是( )。(1)[img=55x29]17e0abbe7d0cf4b.png[/img] (2)[img=124x28]17e0abbe86207a6.png[/img] (3)[img=51x28]17e0abbe8f27381.png[/img] (4)[img=61x28]17e0abbe989993f.png[/img] A: (3)>;(4)>;(1)>;(2) B: (4)>;(3)>;(1)>;(2) C: (3)>;(4)>;(2)>;(1) D: (1)>;(4)>;(3)>;(2)
- 2
设随机变量(X, Y )的分布律为[img=278x153]1802e8d5158f2ae.png[/img]则E(X – Y )=( ). A: 1/2 B: 3/4 C: - 1/4 D: 1
- 3
若f(x)在[-1,1]上连续,其平均值为2,则[img=110x72]17e0b396e26d256.png[/img](). A: 1/4 B: -1 C: 4 D: -4
- 4
设随机变量[img=75x25]1802d5ab02ff46a.png[/img],且已知 E[(X - 1)(X + 2)] = 6,则[img=30x19]1802d5ab0aa816f.png[/img] A: 1 B: 2 C: 3 D: 4