已知x y=3,xy=-7求x² y²1.x²+y²2.(x-y)²
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已知x y=3,xy=-7求x² y²1.x²+y²2.(x-y)²
已知x y=3,xy=-7求x² y²
1.x²+y²
2.(x-y)²
已知x y=3,xy=-7求x² y²1.x²+y²2.(x-y)²
你是要问x+y=3,xy=-7求x²+y²吗?
x²+y²
=x²+y²+2xy-2xy
=(x+y)²-2xy
=9+14
=23
x²+y²=(x+y)²-2xy
(x-y)² =(x+y)²-4xy
已知x y=3,xy=-7求x² y²
你把题目再写一遍可以吗?