x-y=2,x方+y方=10,求xy,(x+y)^2,x+y
问题描述：
x-y=2,x方+y方=10,求xy,(x+y)^2,x+y
答
x-y=2 → (x-y)方=4 → x方+y方-2xy=4 →
xy=(x方+y方-4)/2=(10-4)/2=3
(x+y)^2= x方+y方+2xy=10+2×3=16
x+y=(x+y)^2开方=±4非常感谢请你采纳