若x-y=2,x²-y²=10,则3x-y＝

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若x-y=2,x²-y²=10,则3x-y＝若x-y=2,x²-y²=10,则3x-y＝若x-y=2,x²-y²=10,则3x-y＝解x&#

若x-y=2,x²-y²=10,则3x-y＝
若x-y=2,x²-y²=10,则3x-y＝

若x-y=2,x²-y²=10,则3x-y＝
解
x²-y²=10
(x-y)(x+y)=10
∵x-y=2 ①
2(x+y)=10
∴x+y=5 ②
①×2+②得：3x-y=9