问答题 Directions: You have a close foreign friend. He asked you to subscribe to a copy of China Daily for him because he will leave away from China for one month. Now write a letter to the circulation department of the newspaper: 1) inquiry about detailed information, 2) and expressing complimentary remarks. Write your letter in no less than 100 words. Write it neatly on ANSWER SHEET 2. Do not sign your own name at the end of the letter, use "Li Ming" instead. Do not write the address.
问答题求由方程2x2+2y2+z2+8xz-z+8=0所确定的函数z(x，y)的极值．
问答题
问答题设三阶矩阵A满足Aα
i
=iα
i
(i=1，2，3)，其中列向量α
1
=(1，2，2)
T
，α
2
=(2，-2，1)
T
，α
3
=(-2，-1，2)
T
，试求矩阵A．
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问答题
问答题求
问答题
问答题设α=(1，1，-1)T是的一个特征值．(Ⅰ)确定参数a，b及特征向量所对应的特征值；(Ⅱ)问A是否可以对角化?说明理由．
问答题
问答题
问答题用变换能够把方程，化简为，求a的值．
问答题设二次型
问答题
问答题设f(x)在[0,1]上具有二阶连续导数，且f(0)=f(1)=0，当x∈(0,1)，f(x)≠0．证明：
问答题
问答题设f(x)在[a，b]上连续可导，证明：
问答题设y=y(x)，z=z(x)，由
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问答题设