如果x2+xy=2,xy+y2=-1,则x2-y2=______,x2+2xy+y2=______.
题型:填空题难度:一般来源:不详
如果x2+xy=2,xy+y2=-1,则x2-y2=______,x2+2xy+y2=______. |
答案
(1)∵x2-y2=x2+xy-xy-y2=x2+xy-(xy+y2) 而x2+xy=2,xy+y2=-1, ∴x2-y2=2-(-1)=3; (2)∵x2+2xy+y2=x2+xy+xy+y2, 而x2+xy=2,xy+y2=1, ∴x2+2xy+y2 =x2+xy+xy+y2 =2-1 =1; 故答案为:3,1. |
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