一道数学题
x^2+xy=2,y^2+xy=5,则1/2x^2+xy+1/2y^2的值是多少?
参考答案:x^2+xy=2,y^2+xy=5
(x+Y)^2=7
所以1/2x^2+xy+1/2y^2
=1/2(x+y)^2
=1/2*7
=7/2
=3.5
x^2+xy=2,y^2+xy=5,则1/2x^2+xy+1/2y^2的值是多少?
参考答案:x^2+xy=2,y^2+xy=5
(x+Y)^2=7
所以1/2x^2+xy+1/2y^2
=1/2(x+y)^2
=1/2*7
=7/2
=3.5