下列计算正确的是()A.(x+y)²=x²+y² B. (x-y)²=x²-2xy-y² C.(x+2y)(x-2y)=x²-2y² D.(-x+y)²=x²-2xy+y²分解因式:2x²-8分解因式:16-8(x-y)+(x-y)
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下列计算正确的是()A.(x+y)²=x²+y² B. (x-y)²=x²-2xy-y² C.(x+2y)(x-2y)=x²-2y² D.(-x+y)²=x²-2xy+y²分解因式:2x²-8分解因式:16-8(x-y)+(x-y)
下列计算正确的是()A.(x+y)²=x²+y² B. (x-y)²=x²-2xy-y² C.(x+2y)(x-2y)=x²-2y² D.(-x+y)²=x²-2xy+y²
分解因式:2x²-8
分解因式:16-8(x-y)+(x-y)²=_____
已知x+y=3 xy=-2 求x-y的值
就这么少 求全对?
下列计算正确的是()A.(x+y)²=x²+y² B. (x-y)²=x²-2xy-y² C.(x+2y)(x-2y)=x²-2y² D.(-x+y)²=x²-2xy+y²分解因式:2x²-8分解因式:16-8(x-y)+(x-y)
下列计算正确的是D.(-x+y)²=x²-2xy+y²
分解因式:2x²-8=2(x²-4)=2(x+2)(x-2)
分解因式:16-8(x-y)+(x-y)²=(4-x+y)²
已知x+y=3 xy=-2
(x-y)²=(x+y)²-2xy=3²-2×(-2)=13
∴x-y=±√13