已知(-x+6):(x-y):(4x+y)=3:14:1,求x+y的值
问题描述:
已知(-x+6):(x-y):(4x+y)=3:14:1,求x+y的值
答
(:号同/号是同等)
所以(-x+6): (x-y): (4x+y)=3:14:1
(-x+6)/(x-y)=3/14
交叉相乘3x-3y=-14x+84
17x-3y=84 ①
(x-y)/(4xy)=14
交叉相乘x-y=56x+14y
-55x=15y
-11x=3y ②
联立方程17x+11x=84
4x=12
x=3 代入②
y=-11
x+y=-8
答
1、(-x+6):(x-y):(4x+y)=3:14:1则3*(4x+y)=6-x;3*(x-y)=14*(6-x)
2、整理两个方程得:13x+3y=6;17x-3y=84,两式相加得30x=90,x=3,则y=-11,x+y=-8
答
(-x+6):(4x+y)=3:1,可得13x+3y=6
(x-y):(4x+y)=14:1,可得11x+3y=0
所以,上面新得两式相减则得,2x=6,x=3,则y=-11
x+y=-8