1.如果实数a,b,c满足^2+(b)^2+(c)^2=9,那么代数式^2+(b)^2+(c)^2=9的最大值是_______.2.已知实数a,b,c满足^2+(b)^2+(c)^2=9,^2+(b)^2+(c)^2=9,^2+(b)^2+(c)^2=9,则^2+(b)^2+(c)^2=9的最小值是_______.

12.试用向量证明不等式:-|||-sqrt ({{a)_(1)}^2+({a)_(2)}^2+({a)_(3)}^2}sqrt ({{b)_(1)}^2+({

下列离子的电子构型可以用[ ] 3(d)^5 表示的是 () 。-|||-(A) ^2+ (B) ^2+ (C) ^2+ (D) ^2+

(B) (n-1)(S)^2+(overline {X)}^2 (C) (S)^2+(overline {X)}^2. (D) dfrac (n-1)(n)(S

设a,b, in R 证明: ^2+(b)^2+(c)^2=ab+ac+bc 的充要条件是 =b=c.

求旋转曲面=(x)^2+(y)^2在点=(x)^2+(y)^2处的法线方程A.=(x)^2+(y)^2B.=(x)^2+(y)^2C.=(x)^2+(y)^2D

dfrac (dy)(dx)=(x)^2+(y)^2 B . dfrac (dy)(dx)=(x)^2+(y)^2 C .dfrac (dy)(dx)=(x)^

1.设A,B,C均为n阶方阵,且 =BC=CA=E, 则 ^2+(B)^2+(C)^2 等于 ()-|||-(A)3E (B)2E (C)E (D)0

D是圆形区域^2+(y)^2leqslant 4，则估计^2+(y)^2leqslant 4（）A:^2+(y)^2leqslant 4B:^2+(y)^2le

( A ) = (x,y,z)|{x)^2+(y)^2+(z)^2=(a)^2,zgeqslant 0} ( B ) = (x,y,z)|{x)^2+(y)^

设=sqrt ({x)^2+(y)^2+(z)^2} 则|div(grad)|(1,0,1)= () .-|||-(A) -sqrt (2) (B) sqrt