丨3x+2y+3丨+(2x-4y-14)²=0,求x y的值.
问题描述：
丨3x+2y+3丨+(2x-4y-14)²=0,求x y的值.
答
因为丨3x+2y+3丨>=0,(2x-4y-14)²>=0,
而丨3x+2y+3丨+(2x-4y-14)²=0,
所以
丨3x+2y+3丨=0,(2x-4y-14)²=0,
3x+2y+3=0---(1)
2x-4y-14=0---(2)
(1)×2-(2)×3
16y+48=0
y=-3
将y=-3带入(1)
3x+2×(-3)+3=0
3x-3=0
x=1