{4x+8(x+y)=480 {4y+9(x+y)=480不要复制黏贴的

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{4x+8(x+y)=480 {4y+9(x+y)=480不要复制黏贴的
{4x+8(x+y)=480 {4y+9(x+y)=480
不要复制黏贴的

{4x+8(x+y)=480 {4y+9(x+y)=480不要复制黏贴的
4x+8(x+y)=4x+8x+8y=12x+8y=480, 即y=60-1.5x
4y+9(x+y)=4y+9x+9y=13y+9x=480
把y=60-1.5x代入上式得13（60-1.5x）+9x=480,解得x=200/7 y=120/7

楼上答案错误。
是7/200和7/120

详细过程```
4x+8(x+y)=480
4y+9(x+y)=480
2式相减
x-y-(x+y)=0
-2y=0
y=0
x=40

解方程组{4x+8(x+y)=480,4y+9(x+y)=480 9y=3x-(x-1),4(x+y)-(2x+4)=8y 81/8*(-x-y)^6*(x-y)^3*4/9(x+y)^4*(y-x)^2 4(x-y)-3(x-y)=9 5(x-y)+2(x-y)=11 3(x+y)-2(x-y)=11 4(x+y)+3(x-y)=9 X+Y=9 8X+4Y=56 4x+8(x+y)=840 4y+9(x+y)=840 求x ,y 9x^2+4y^2-12x-8y+8=0 [(x+2y)(x-2y)-(x-2y)^2+8y(x+y)]除以4x= 4x+8（x+y）=480 4y+9(x+y)=480 = = {4x+8(x+y)=480 {4y+9(x+y)=480不要复制黏贴的计算：(x-y)^8÷(y-x)^4×(x-y) 化简(x+y)+(2x+1/2y)+(3x+2/3y)+(4x+3/4y)+...+(9x+8/9y)=? 化简：(-4x+3y)(-3y-4x)-(2x+3y)(8x-9y),其中,x=-3,y=-2 3x+2=y 5x+4=y 7x+6=y 9x+8=y 11x=y 联立方程有的话 3x+2=y 5x+4=y 7x+6=y 9x+8=y 11x=y 3x+2=y 5X+4=Y 7X+6=Y 9X+8=y 11x=y要如何计算 3x+2=y 5x+4=y 7x+6=y 9x+8=y 11x=y怎么解