已知（x+y)2=5,（x+y）2=1.（1）求x、y两数的平方和.（2）求x、y两数的积.

已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 已知x*x+4x+y*y-2y+5=0,则x*x+y*y=? 1.已知:x-2y=3,求[(3x+2y)(3x-2y)-(x+2y)(5x-2y)]除4x 的值 1.y=x^5+5^x+x^x+lgx 2.y=xe^x^2求y'' 3.已知y=e^f(x),则y''= 4.已知y=(1+x)^x,求导数y' 已知x=2,y=3,求代数式（x-y）*（x-y）^3*(x-y)^5*……*(x-y)^11 已知x-y/x=x/x-2y（y不等于0）,求x：y的值 已知x-y=3,求[（x+y)(x-y)-(x-y)^2+2y(x-y)]除以的值 已知3x =2y 求x/x+y+y/x-y-y²/x²-y² x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 已知f(x+y,y/x)=x^2-y^2,则f(x,y)= 已知|x|=2,|y|=3,|x+y|=-(x+y)求x-y 已知x≠y,x^2-x=y^2-y,求x+y的值. 已知x>0,Y>0,如何证x^2/y+y^2/x>=x+y 已知（x+y）2 =2,(x-y)3 =3,求(x+y)7(x-y)2(x+y)3(y-x)4 的值 已知方程组{(X+Y)-3(X-Y)=7,2(X+Y)+(X-Y）=-7}则(X+Y)(X-Y)= 已知X.x+y.y-4x+2y+5=0,求4X.X-12X Y+9Y.y的值 已知x^2+y^2-4x-2y+5=0,求log（x）y^x的值 已知（x+2）^2+|x+y+5|=0,求3x^2y-[2x^2y-(2xy-x^2y)-4x^2]-xy