丨x丨=3,丨y丨=5,且丨x+y丨=-x-y,求x-y的值

2025-04-28 14:43:42
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回答1:

丨x丨=3,x=±3
丨y丨=5,y=±5

丨x+y丨=-x-y = -(x+y)
∴x+y<0
∴x=±3,y=-5
∴x-y = ±3-(-5) = 2,或8