x-y=2,x方+y方=10,求xy,(x+y)^2,x+y

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x-y=2,x方+y方=10,求xy,(x+y)^2,x+yx-y=2,x方+y方=10,求xy,(x+y)^2,x+yx-y=2,x方+y方=10,求xy,(x+y)^2,x+yx-y=2→(x-y

x-y=2,x方+y方=10,求xy,(x+y)^2,x+y
x-y=2,x方+y方=10,求xy,(x+y)^2,x+y

x-y=2,x方+y方=10,求xy,(x+y)^2,x+y
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