l 2x-y+7l+lx+2y-2l=0? 求x.y
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2006-09-09 14:51:26 · 3 個解答 · 發問者 ? 3 in 電腦與網際網路 ➔ 程式設計
前面那個很像1的是絕對質
2006-09-09 15:26:18 · update #1
l 2x-y+7l+lx+2y-2l=0表示2x-y+7=0而且x+2y-2=0,
剩下的工作就是解兩元一次聯立方程式:
2x-y=-7,x+2y=2,所以x=(-12/5)=-2.4,y=(11/5)=2.2
2006-09-09 15:43:07 · answer #1 · answered by ? 5 · 0⤊ 0⤋
Since |x|>=0, for any real number x.
|x|+|y|=0, x,y any real number, then the only solution is x=0 and y=0.
So l 2x-y+7l+lx+2y-2l=0 becomes
2x-y+7=0 and x+2y-2=0
2(2x-y+7)=2*0 <=(1)
x+2y-2=0 <=(2)
(1)+(2) => 5x+12=0=> x=-12/5
-12/5+2y-2=0=> y=11/5
2006-09-09 17:07:54 · answer #2 · answered by ? 4 · 0⤊ 0⤋
|任何數|=正數
(正數+正數)不等於 0
|2x-y+7|=0
|x+2y-2|=0
2x-y+7=0…(1)
x+2y-2=0…(2)
兩式聯立得解
2006-09-09 16:25:46 · answer #3 · answered by Big_John-tw 7 · 0⤊ 0⤋