计算：(3x+y+2)(3x-y-2).

计算：（3x+y+2）（3x-y-2）．计算：（3x+y+2）（3x-y-2）．

1.计算:(3x+y+2)(3x-y-2).2.已知(3x+y+2)(3x-y-2).求（a+b-c）²。3.设x>0,且(3x+y+2)(3x-y-2).求(

已知函数 =(x)^3y+3(x)^2(y)^2-x(y)^3 ,则 =(x)^3y+3(x)^2(y)^2-x(y)^3 ( ) A =(x)^3y+3

A (x,y)=(x)^3-6(x)^2y-3x(y)^2+2(y)^3 . B (x,y)=(x)^3-6(x)^2y-3x(y)^2+2(y)^3 . C

以下函数数中,是(x,y)=(x)^3-3x(y)^2-y的共轭调和函数的是(x,y)=(x)^3-3x(y)^2-y (x,y)=(x)^3-3x(y)^2-

10.已知线性变换-|||- ) (x)_(1)=2(y)_(1)+2(y)_(2)+(y)_(3) (x)_(2)=3(y)_(1)+(y)_(2)+5(y

(7) dfrac (dy)(dx)=dfrac (2{x)^3+3x(y)^2+x}(3{x)^2y+2(y)^3-y}

3.已知两个线性变换-|||- ) (x)_(1)=2(y)_(1)+(y)_(3), (x)_(2)=-2(y)_(1)+3(y)_(2)+2(y)_(3)

曲线y=(x-1 )3√x^2的凹区间为（ ）y=(x-1 )3√x^2y=(x-1 )3√x^2y=(x-1 )3√x^2y=(x-1 )3√x^2曲线的凹区

3.已知两个线性变换-|||- ) (x)_(1)=2(y)_(1)+ (y)_(3) (x)_(2)=-2(y)_(1)+3(y)_(2)+2(y)_(3