已知| 3-y | + | x+y | =0,求x+y/xy的值(/是分数线,不会打分数线 所以用的/)
问题描述:
已知| 3-y | + | x+y | =0,求x+y/xy的值(/是分数线,不会打分数线 所以用的/)
答
∵| 3-y | + | x+y | =0 又∵| 3-y |≥0| x+y |≥0∴| 3-y |=0 y=3 ∴ | x+y |=0x+y=0x= -y = -3x+y/xy= -3+3/(-9)= -3-1/3= -3又1/3 = -10/3