如果x+y=0,xy=-7,x2y+xy2=_,x2+y2=_.
问题描述:
如果x+y=0,xy=-7,x2y+xy2=______,x2+y2=______.
答
解;∵x+y=0,xy=-7
∴x2y+xy2=xy(x+y)=-7×0=0
x2+y2=(x+y)2-2xy=02-2×(-7)=0+14=14.