来自董飞垚的问题
已知x+y=4,xy=3,求下列各式的值:(1)(x-y)2;(2)x2y+xy2.
已知x+y=4,xy=3,求下列各式的值:
(1)(x-y)2;
(2)x2y+xy2.
1回答
2020-07-31 22:09
已知x+y=4,xy=3,求下列各式的值:(1)(x-y)2;(2)x2y+xy2.
已知x+y=4,xy=3,求下列各式的值:
(1)(x-y)2;
(2)x2y+xy2.
(1)∵x+y=4,xy=3,
∴(x-y)2=x2-2xy+y2=(x+y)2-4xy=16-12=4;
(2)∵x+y=4,xy=3,
∴x2y+xy2=xy(x+y)=12.