如果极限值存在，求极限值，若果不存在，说明理由，[tex=6.929x2.786]MhC0sa4kP8ihnFHLNuEHS7TErnC8/dxgufV4YB15cKQwhsG5BsKiPoLCcv+w/3oYOsRErl5qFqkpmsGzwYJZKS3HIsCZ6QvXe1uRzSakNak=[/tex] .

求直线[tex=6.929x2.786]7EJHVCtO2IWq3KpdB+jQsphVXBGNiuZV4DCgcOGs4rV3xBM0iJA3r87Ig8LvbWbCpunjM9+MmuLaBUGuka1ZFw==[/tex]，在平面[tex=5.714x1.286]JNGTfvf9WREp6OanBKHgpw==[/tex]上的投影直线方程．

分别用雅可比迭代与高斯-赛德尔迭代求解下面方程组：[tex=6.929x2.786]fnpmC2J6JmQBLyo5NmGAz5Bo72kJfJcJdFHkIrF1KOon+i6wA4NcqJpDRH6666ochr4ILxJSnLytfxO4jmHanfNmuyZhTEaYQkEafMTbWhg=[/tex]

加工方程组[tex=6.929x2.786]7EJHVCtO2IWq3KpdB+jQskLBjE2+hiUc9exjlngcjAJtw5daQN3iMUfPuyf+0fz8eccK4GINXDEbz7UuRwWE6Wev2VW3oN3R9O/wnrqutCQ=[/tex]，比如调换方程组的排列顺序，以保证迭代过程的收敛性。

某因果离散系统状态方程的系统矩阵[tex=6.929x2.786]s4iFwJNC/D8533R68c8pxuGLEzLa+4s2ppmwjkgNLrti4GNZGVTSzsIls+NW3SzbsZd3Pjc3QzNtmgpKhSc6zg==[/tex], 当[tex=0.429x1.0]Q2fWySASH/4Xf2eu85OwAQ==[/tex]为何值时系统是稳 定的?

设一平面过原点及从点[tex=4.0x1.357]S9hJ5sUaq41hwn1ZjN8r/Q==[/tex]到直线[tex=6.929x2.786]7EJHVCtO2IWq3KpdB+jQsmgjIEhOqQR2YssFWjZw93BKamyd/wP/ffBSOD6WeKnT6Aa1frz3jbgw9Fhx/pcpkgXSaacCrnI+JR6BR0SI3D0=[/tex]的垂线,求此平面方程.

设A为n阶矩阵,α为n维列向盘,记矩阵[tex=6.929x2.786]tAg4kjefm91yBdigy4ffjHx8jmDDBldzTJcZLKMxMJjCH0TboolNzGf/x+p398TbKCn2ii6qZLRQ/aRaz4+vR1QF4FRwy8H+CZ7QfquK6v4=[/tex]，且R(B)= R(A),证明:齐次线性方程Bx=0必有非零解．

利用初等变换求解下列线性方程组：1.[tex=6.929x2.786]LxijgwYJR62XZBuC+wi8DRcKdkqolm2eXLVgvy//O/u9A2/JG2pP6cAetyNE4NQp6lSWCr3QH38K8vT/+H1lhLzkgDD/ch+K1WvEo/MF99z6TVCxNT6wLS2VzbBietHL[/tex]2.[tex=9.357x2.786]LxijgwYJR62XZBuC+wi8DXyxt3Ki6s5RO11440CzklzsSgc0XOctbUZV/rk2Ys/eUW5oD7gp7SUqdUmQGjqDEp4g2sJrNjRykaJAgLdjSq4dIYrqg0pGbtpQlz8PrCF0PA4lOPCxvO+kA/RhYotmfA==[/tex]3.[tex=9.5x5.214]LxijgwYJR62XZBuC+wi8DXyxt3Ki6s5RO11440CzklzsSgc0XOctbUZV/rk2Ys/eVz35SbTpLewMBEApA3y20DeX3Rb9HPYo5YMB9eQvBwPBTq3U571bUFUDZboaFyVSIEiw6w23YXygPc8XhQeEAKWOjxWguijQESqEZOXHTpTotdyts42kuVpXZdOATc8awtwbH9Z65v7Y1ZszVWNKIsAZu9zCKYkfrC47j4miUKI=[/tex]4.[tex=10.286x5.357]fnpmC2J6JmQBLyo5NmGAz5Bo72kJfJcJdFHkIrF1KOpAML8EDuUpA2xoffXblxcOjwNitqeMkP5GUu9D/TJJyMKlwakZj+KdCHulg3XpLz7A+Z+zShr7XhEg/z+K5C8s8YZDdm8qQEq1Z04mUNdQVFg2Z+c1Rohl3DRwiDIsAetE/88da7+wcFEYSMcwkF8UhgpHd7jlqIL4uj5K7KllEQ==[/tex]

下列变量组（）是一个闭回路。 A: {x，x，x，x，x，x} B: {x，x，x，x，x} C: {x，x，x，x，x，x} D: {x，x，x，x，x，x}

以下谓词蕴含式正确的是（）: (∀x) (A(x)→B(x))=>( ∀x)A(x)→(∀x)B(x)|(∀x) (A(x)↔B(x))=>( ∀x)A(x)↔(∀x)B(x)|(∀x)A(x)∨(∀x)B(x)=>( ∀x) (A(x)∨B(x))|(∃x) (A(x)∧B(x))=>(∃x)A(x)∧(∃x)B(x)