填空题由方程确定的隐函数z=z(x，y)在点(1，0，-1)处的微分为dz=________．

填空题 设，是否与对角矩阵相似_______________.

填空题函数f(x，y)=4(x-y)-x 2 -y 2 的极大值点是______．

填空题设f(u，v)二阶连续可偏导，且

填空题设A是4×3矩阵，且A的秩r(A)=2，而则r(AB)=________．

填空题微分方程y'+y=e-xcosx满足条件y(0)=0的解为y=______．

填空题设A是三阶实对称矩阵，其特征值为λ1=3，λ2=λ3=5，且λ1=3对应的线性无关的特征向量为α1=，则λ2=λ3=5对应的线性无关的特征向量为________

填空题设z=ln(x2+y2)，则=________．

填空题数列的最小项的项数n=______．

填空题设每次试验成功的概率为0.2，失败的概率为0.8，设独立重复试验直到成功为止的试验次数为X，则E(X)=______．

填空题函数y=ln(arcsinx)的连续区间为______．

填空题设f"(a)存在，f"(a)≠0，则

填空题设A是n阶矩阵，λ是A的r重特征根，A的对应于λ的线性无关的特征向量是k个，则k满足________

填空题设随机变量X在[-1，2]上服从均匀分布，随机变量则D(Y)=________．

填空题若f(x)=e-x，则=______．

填空题已知级数与广义积分均收敛，则p的取值范围是______．

填空题设，且方程组Ax=0的解空间的维数为2，则a=________．

填空题Today's new Labor Department report showing that the economy lost jobs last month, the first loss this year, seems in stark contrast to where the president and the Congress are focusing their attentions. Congress recessed without extending unemployment benefits, in large measure due to repeated Republican obstruction. The economy is now presenting a strange dichotomy. The corporate sector has returned to rude health, with improved balance sheets and tons of cash. It has helped lead the recovery. (41)______. And yet Washington's response seems to be a collective throwing up of hands. There are a few things the government can do about persistent long-term unemployment. First, it can lessen the pain it causes by expanding the safety net, extending unemployment- insurance benefits so that the long-term unemployed have a source of cash to help them stay current on rent, mortgage, and credit card bills. Second, it can respond to persistent long-term unemployment by enacting policies aimed at creating and preserving jobs. (42)______. But so far? Nothing. And the question is why. First, there's the matter of the uncertain trumpet at the Federal Reserve. Chairman Ben Bernanke didn't seem to do nothing about high unemployment. At the very least, he could have lent moral support to the need for further stimulus—if only out of self-interest. (43)______. And politics clearly has a lot to do with it. On the fringes of the Republican right, there's some stupid behaviors—i.e., Nevada Senate candidate Sharron Angle arguing that laziness and a desire to live large off unemployment checks is responsible for her state's 14 percent unemployment rate. There's some narrow-mindedness. Sen. Ben Nelson, a Democrat from Nebraska, a state where the unemployment rate is about half the national average, joined the Republican obstruction of an extension of unemployment benefits—his constituents don't need it. In the broad center, there's a lot of serious hypocritical nonsense. (44)______. Funny how such integrity never surfaces when legislators vote to spend much larger sums on the wars in Iraq and Afghanistan, on the Medicare prescription drug benefit, and on the Bush tax cuts. (45)______.These efforts have exhausted the policy team and its congressional allies. And perhaps high unemployment is something we'll have to live with, given the way the economy has recovered from recent recessions. The president's budget notes "even with healthy economic growth there is likely to be an extended period of higher- than-normal unemployment lasting for several years." A chart in the budget notes that after the 1991 and 2002 recessions, the turning points for jobs came five and seven quarters, respectively, after the lowest point in growth. If there's a sense that all modern recoveries will be jobless, as companies focus on productivity, then further stimulus provides diminishing economic and political returns. [A] In the White House, there's probably a level of exhaustion and Zen-like acceptance—it pushed through a large stimulus package and monumental health care reform, two heroic measures that are working and whose benefits will continue to phase in over time. [B] For Democrats, there's no way to cut the deficit or find revenue for new initiatives unless they grow. Should Republicans retake control of the House and Senate next year, their first order of business would be to preserve the Bush tax cuts that are set to expire—a move that would make already large deficits even larger and thus render significant tax-reduction impossible. [C] Maybe he wants to be remembered as the Fed chairman who presided over an era of European-level unemployment, when skills eroded, and several graduating classes entered a glutted workforce. [D] Along with many other senators, Nelson opposed the recent benefit extension on the grounds that it was immoral and wrong to enact a $19 billion spending package without offsetting tax increases or spending cuts. [E] But without the mighty American consumer, who generates 70 percent of economic activity, participating to the fullest degree, the recovery will seem weak. Without a healthy jobs market, the recession-shocked consumer won't spend. [F] And he's probably right. Republicans have made the calculation that the weaker the economy and the employment market are in the next few months, the better their prospects for 2010 and 2012 are—and they're right, too. [G] These can take the form of summer jobs programs, enhanced public works programs, aid to strapped municipalities so they can avoid layoffs, and tax cuts and credits for investment and hiring.

填空题函数处的导数值为________．