填空题设总体X～N(2，42)，从总体中取容量为16的简单随机样本，则

填空题设两个随机事件A,B, P(4)=0.5，P(AB)=0.4; 计算P(B|A)=

填空题设总体X的概率密度为，X1，X2，…，Xn为总体X的简单随机样本，其样本方差为S2，则ES2=______．

填空题设B=，则Bn=________．

填空题The time for sharpening pencils, arranging your desk, and doing almost anything else instead of writing has ended. The first draft will appear on the page only if you stop avoiding the inevitable and sit, stand up, or lie down to write. (41)______ Be flexible. Your outline should smoothly conduct you from one point to the next, but do not permit it to railroad you. If a relevant and important idea occurs to you now, work it into the draft. (42)______ Grammar, punctuation, and spelling can wait until you revise. Concentrate on what you are saying. Good writing most often occurs when you are in hot pursuit of an idea rather than in a nervous search for errors. (43)______ Your pages will be easier to keep track of that way, and, if you have to clip a paragraph to place it elsewhere, you will not lose any writing on the other side. If you are working on a word processor, you can take advantage of its capacity to make additions and deletions as well as move entire paragraphs by making just a few simple keyboard commands. Some software programs can also check spelling and certain grammatical elements in your' writing. (44)______ These printouts are also easier to read than the screen when you work on revisions. Once you have a first draft on paper, you can delete material that is unrelated to your thesis and add material necessary to illustrate your points and make your paper convincing. The student who wrote "The A & P as a State of Mind" wisely dropped a paragraph that questioned whether Sammy displays chauvinistic attitudes toward women. (45)______ Remember that your initial draft is only that. You should go through the paper many times—and then again working to substantiate and clarify your ideas. You may even end up with several entire versions of the paper. Rewrite. The sentences within each paragraph should be related to a single topic. Transitions should connect one paragraph to the next so that there are no abrupt or confusing shifts. Awkward or wordy phrasing or unclear sentences and paragraphs should be mercilessly poked and prodded into shape.[A] To make revising easier, leave wide margins and extra space between lines so that you can easily add words, sentences, and corrections. Write on only one side of the paper.[B] After you have clearly and adequately developed the body of your paper, pay particular attention to the introductory and concluding paragraphs. It's probably best to write the introduction last, after you know precisely what you are introducing. Concluding paragraphs demand equal attention because they leave the reader with a final impression.[C] It's worth remembering, however, that though a clean copy fresh off a printer may look terrific, it will read only as well as the thinking and writing that have gone into it. Many writers prudently store their data on disks and print their pages each time they finish a draft to avoid losing any material because of power failures or other problems.[D] It makes no difference how you write, just so you do. Now that you have developed a topic into a tentative thesis, you can assemble your notes and begin to flesh out whatever outline you have made.[E] Although this is an interesting issue, it has nothing to do with the thesis, which explains how the setting influences Sammy's decision to quit his job. Instead of including that paragraph, she added one that described Lengel's crabbed response to the girls so that she could lead up to the A & P "policy" he enforces.[F] In the final paragraph about the significance of the setting in "A & P," the student brings together the reasons Sammy quit his job by referring to his refusal to accept Lengel's store policies.[G] By using the first draft as a means of thinking about what you want to say, you will very likely discover more than your notes originally suggested. Plenty of good writers don't use outlines at all but discover ordering principles as they write. Do not attempt to compose a perfectly correct draft the first time around.

填空题设f(x)=3x+5，则f[f(x)-2]=______.

填空题计算下列广义积分

填空题函数的连续区间为________.

填空题设z=ln(x 2 +y)，则全微分dz=______．

填空题袋中有4个球，其中有2个白球和2个黑球，从中任意取出2个球，如果取出的2个球中恰好是1个白球和1个黑球就停止试验，否则将这2个球放回袋中重新抽取2个球，直到取到1个白球和1个黑球为止．用X表示抽取次数，则数学期望EX=______．

填空题设随机变量X，Y，Z相互独立，且X～U[-1，3]，，Z～N(1，32)，且随机变量U=X+2Y-3Z+2，则D(U)=________．

填空题设区域D由y轴，y=x，y=1所围成，则．

填空题 二次型的矩阵形式为 ______________________________________________.

填空题设f(x)在[0，1]上连续，且，则

填空题z=f(u，x，y)，u=x2ey，其中f具有连续的二阶偏导数，则

填空题函数y=ln(1-2x)在x=0处的n阶导数y(n)(0)=______．

填空题 微分方程x(y')2-2xy'+x=0的阶数是______．

填空题已知f(x)为连续函数，且

填空题＝________．