您所在的当前位置：高中数学试题 >

平面向量数量积的意义

> 已知 =(1,2,3), =（3，0，-1）， = 给出下列等式： ①∣ ∣=∣ ∣ ② = ③ = ④ = 其中正确的个数是 A．1个 B．2个 C．3个 D．4个

问题：

发布时间：2024-09-07

已知 =(1,2,3), =（3，0，-1）， = 给出下列等式：
①∣ ∣=∣ ∣ ② = ③ =
④ =
其中正确的个数是

A．1个 B．2个 C．3个 D．4个

参考答案：

提问用户：9A***i1s

可能感兴趣的题目：

1 图所示是甲、乙两物体从同一地点，沿同一方向做直线运动的υ-t图象，由图象可以看出 A.这两个物体两次相遇的时刻分别是1s末和4s末 B.这两个物体两次相遇的时刻分别是2s末和6s末 C.两物体相距最远的时刻是2s末 D.4s末以后甲在乙的前面
2 某校兴趣小组用如图Ⅰ装置制取漂白液（气密性已检验，试剂已添加），并研究其相关性质。实验操作和现象：打开分液漏斗的活塞，缓缓滴加一定量浓盐酸，点燃酒精灯；一段时间后，关闭分液漏斗的活塞，熄灭酒精灯。（1）烧瓶中反应的化学方程式是。（2）饱和食盐水的作用是。（3）若用图Ⅱ装置收集多余的氯气，请在虚线框内画出该装置简图。（4）该小组同学用上述装置制得的漂白液中NaClO的浓度偏低。查阅资料：在溶液中发生反应：（a）Cl 2（g）＋2NaOH（aq）═ NaCl（aq）＋NaClO（aq）＋H 2O（l）H 1=－101.1kJ/mol （b）3NaClO（aq）═2NaCl（aq）＋NaClO 3（aq）H 2=－112.2kJ/mol 反应（a）的反应速率很快，反应（b）在室温下较慢根据资料，请对图Ⅰ装置提出改进建议：。（5）修改方案后，该小组同学制得了较高浓度的NaClO溶液。他们把漂白液和滴有酚酞的红色Na 2SO 3溶液混合后，得到无色溶液。提出猜想：ⅰ．NaClO把Na 2SO 3氧化了 ⅱ．NaClO把酚酞氧化了 ⅲ．NaClO把Na 2SO 3和酚酞均氧化了 ①下列实验方案中可以证明NaClO氧化了Na 2SO 3的是。 a．向混合后的溶液中加入过量盐酸 b．向混合后的溶液中加入过量盐酸，再加入氯化钡溶液 c．向混合后的溶液中加入过量硝酸，再加入硝酸银溶液 d．向混合后的溶液中加入氢氧化钡溶液，再加入过量盐酸 ②为证明NaClO氧化了酚酞，可进行的实验是。
3 下列各项属于我国特产珍稀动物的是 ①白鳍豚 ②鸭嘴兽 ③中华鲟 ④大熊猫 ⑤袋鼠 ⑥扬子鳄 A.①②③④ B.②④⑤⑥ C.①③④⑥ D.②③④⑤
4 完形填空。 I am a mother of three (ages 14, 12 and 3) and have recently completed my college degree. The last 1 I had to take was Sociology and the last project of the term was called "Smile". The class was asked to go out and smile at three people and note down their 2 . Soon after we were 3 the project, my husband, youngest son and I went out to McDonald"s. We were standing in line, waiting to be 4 . When all of a sudden everyone around us began to back away. As I turned around, I smelled a 5 "dirty body" smell and there 6 me stood two poor homeless men. As I looked down at the short gentleman close to me, he was " 7 " - his beautiful sky blue eyes were full of the light as he searched for 8 . He said "Good day" as he 9 the few coins he had been holding. The young lady at the counter asked him what they wanted. He said, "Coffee is 10 , Miss," because that was what they could afford. To sit in the restaurant and 11 up, they had to buy something. Then I really felt it - the 12 was so great that I almost reached out and embraced the little man with the blue eyes. That was when I noticed all eyes in the restaurant were 13 me, judging my every action. I smiled and asked for two more breakfast meals on a 14 tray. I then walked to the table that the men had chosen as a 15 spot, put the tray on the table and laid my hand on the blue eyed gentleman"s cold hand. He looked 16 at me, with tears in his eyes, and said, "Thank you." I patted his hand and said, "I did not do this for you. God is here working 17 me to give you hope." I returned to college with this story in hand. I 18 "my project" and later the instructor read it to the class. In this way I had 19 my classmates and the people around me. And I graduated with one of the most meaningful lessons in my life - 20 acceptance. ( ) 1. A. class ( ) 2. A. attitude ( ) 3. A. arranged ( ) 4. A. greeted ( ) 5. A. familiar ( ) 6. A. around ( ) 7. A. eating ( ) 8. A. agreement ( ) 9. A. counted ( )10. A. little ( )11. A. cheer ( )12. A. urge ( )13. A. lightedon ( )14. A. separate ( )15. A. relying ( )16. A. up ( )17. A. over ( )18. A. turned over ( )19. A. pleased ( )20. A. conditional B. school B. thought B. assumed B. served B. pleasant B. besides B. drinking B. recognition B. showed B. some B. warm B. anger B. stared at B. big B. pleasing B. down B. out B. handed out B. confused B. unconditional C. work C. mind C. assigned C. cheated C. terrible C. behind C. crying C. acceptance C. grasped C. any C. dress C. sickness C. fixed on C. single C. staying C. around C. through C. turned out C. frightened C. emotional D. degree D. reaction D. suggested D. seated D. strange D. beyond D. smiling D. welcome D. made D. all D. take D. sadness D. looked at D. special D. resting D. aside D. across D. handed in D. touched D. devoted
5 如图所示，物体A与物体B置于光滑水平面上，其质量m A>m B，A、B间有一细绳连接，且有与A、B不连接的被压缩的轻弹簧，整个装置处于静止状态，现将细绳烧断，而后弹簧伸展将A、B弹开，以下说法正确的是（） A．此过程中，B受弹力大小比A受弹力大 B．此过程中，弹力对B的冲量大小比对A的冲量大 C．此过程中，弹力对B做功比对A做功多 D．开始运动后，任一时刻B的瞬时速度大小始终比A的瞬时速度大
6 某车站上并排停着两列待发的列车甲和乙，当甲列车车厢里的人从窗口看到乙列车向南移动，从车厢另一侧的窗口看到田野上的树木也向南移动，但比看乙列车移动的速度慢，如果以地面为参照物，上述事实说明 A.甲乙两列车同时开始运动，甲列车向北运动，乙列车向南运动 B.甲列车开始向北运动，乙列车未动 C.甲乙列车同时开始运动，都向北行驶 D.甲乙列车同时开始运动，甲列车向南运动，乙列车向北运动
7 与我国西北地区和北方地区的分界大致吻合的是 A.第二级阶梯与第三级阶梯分界线 B.亚热带与暖温带分界线 C.外流区与内流区分界线 D.季风区与非季风区分界线
8 英国科学家____________（选填“牛顿”、“卡文迪许”）利用扭秤装置，第一次测出了引力常量G，引力常量G=____________Nm 2/kg 2。
9 下列说法正确的是（　　） A．25℃时NH4Cl溶液的Kw大于100℃时NaCl溶液的Kw B．SO2通入碘水中，反应的离子方程式为SO2+I2+2H2O═SO32-+2I-+4H+ C．加入铝粉能产生H2的溶液中，可能存在大量的Na+、Ba2+、AlO2-、NO3- D．100℃时，将pH=2的盐酸与pH=12的NaOH溶液等体积混合，溶液显中性
10 氯化铜是一种广泛用于生产颜料、木材防腐剂等的化工产品。某研究小组用粗铜（含杂质Fe）按下述流程制备氯化铜晶体（CuCl 2·xH 2O）。（1）实验室采用如图所示装置，可使粗铜与Cl 2反应转化为固体1（部分加热仪器和夹持装置已略去）。该装置中仪器a的名称是。装置b中发生反应的离子方程式是。该装置存在一定的安全隐患，消除该安全隐患的措施是。（2）操作Ⅱ中应控制的pH范围为，其目的是。已知：（3）操作Ⅲ的程序依次为、、过滤、自然干燥．得到CuCl 2·xH 2O晶体。（4）若制备的氯化铜晶体经检验含有FcCl 2，其原因可能是，试提出两种不同的改进方案：① ；② 。