第1个回答 2006-10-26
(x-y)^2-(x^2+y^2)
=(x^2-2xy+y^2)-(x^2+y^2)
=-2xy
x-y=2,x^2+y^2=4
(x-y)^2-(x^2+y^2)=2^2-4=0
-2xy=0,xy=0
当x=0,y=-2
x^1992+y^1992=(-2)^1992=2^1992
当y=0,x=2
x^1992+y^1992=2^1992
x^1992+y^1992的值是(2^1992 )
第2个回答 2006-10-26
x-y=2,x=y+2,代入x^2+y^2=4:(y+2)^2+y^2=4
y^2+4y+4+y^2=4,2y^2+4y=0,y^2+2y=0,y(y+2)=0
y1=0,y2=-2,∴x1=2,x2=0代入x^1992+y^1992
得x^1992+y^1992=2^1992