当(x+y)²=36,(x-y)²=16,求xy与x²+y²的值

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当(x+y)²=36,(x-y)²=16,求xy与x²+y²的值当(x+y)²=36,(x-y)²=16,求xy与x²+y

当(x+y)²=36,(x-y)²=16,求xy与x²+y²的值
当(x+y)²=36,(x-y)²=16,求xy与x²+y²的值

当(x+y)²=36,(x-y)²=16,求xy与x²+y²的值
(X+y)²=36
x²+2xy+y²=36(1)
(x-y)²=16
x²-2xy+y²=16(2)
(1)-(2)
4xy=20
xy=5
(1)+(2)
2(x²+y²)=52
x²+y²=29