1 .a/b =c/d =e/f = 1/3 ,则 a -2c +3e / b - 2d + 3f 2.x / 2 =y / 3 =z /4 ,则 x+y-z / x+y+z 3.已知 a/ b =c/d =e/f =2/3 ,求值 (1） a+c/b+d (2) 2a-c-5e/2b -d -5f

1 .a/b =c/d =e/f = 1/3 ,则 a -2c +3e / b - 2d + 3f 2.x / 2 =y / 3 =z /4 ,则 x+y-z / x+y+z 3.已知 a/ b =c/d =e/f =2/3 ,求值 (1） a+c/b+d (2) 2a-c-5e/2b -d -5f
1 .a/b =c/d =e/f = 1/3 ,则 a -2c +3e / b - 2d + 3f
2.x / 2 =y / 3 =z /4 ,则 x+y-z / x+y+z
3.已知 a/ b =c/d =e/f =2/3 ,求值 (1） a+c/b+d (2) 2a-c-5e/2b -d -5f

1 .a/b =c/d =e/f = 1/3 ,则 a -2c +3e / b - 2d + 3f 2.x / 2 =y / 3 =z /4 ,则 x+y-z / x+y+z 3.已知 a/ b =c/d =e/f =2/3 ,求值 (1） a+c/b+d (2) 2a-c-5e/2b -d -5f
1、由 a/b =c/d =e/f = 1/3得：a=1/3b,c=1/3d,e=1/3f
所以a -2c +3e / b - 2d + 3f
=（1/3b-2/3d+3/3f)/(b-2d+3f)
=1/3(b-2d+3f)/(b-2d+3f)
=1/3
2、设x / 2 =y / 3 =z /4=k,则x=2k,y=3k,z=4k
所以 x+y-z / x+y+z
=(2k+3k-4k)/(2k+3k+4k)
=k/9k
=1/9
3、由a/ b =c/d =e/f =2/3得：a=2/3b,c=2/3d,e=2/3f
所以（1） a+c/b+d
=2/3b+2/3d/b+d
=2/3(b+d)/b+d
=2/3
(2）2a-c-5e/2b -d -5f
=2/3(2b-d-5f)/2b-d-5f
=2/3

1.因为a/b =c/d =e/f = 1/3 ，所以b=3a,d=3c,f=3e,则a -2c +3e / b - 2d + 3f =（a-2c+f)/(3a-6c+3f)=1/3
2.因为 x / 2 =y / 3 =z /4 ，所以x=2y/3,z=4y/3,则 x+y-z / x+y+z =(2y/3+y-4y/3)/(2y/3+y+4y/3)=(y/3)/3y=...

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1.因为a/b =c/d =e/f = 1/3 ，所以b=3a,d=3c,f=3e,则a -2c +3e / b - 2d + 3f =（a-2c+f)/(3a-6c+3f)=1/3
2.因为 x / 2 =y / 3 =z /4 ，所以x=2y/3,z=4y/3,则 x+y-z / x+y+z =(2y/3+y-4y/3)/(2y/3+y+4y/3)=(y/3)/3y=1/9
3.(1)因为 a/ b =c/d =e/f =2/3 ,所以b=3a/2,d=3c/2,则 a+c/b+d =（a+c）/(3a/2+3c/2)=2/3
(2)因为 a/ b =c/d =e/f =2/3 ，所以2a=3b/4,c=2/3d,e=2/3f,则 2a-c-5e/2b -d -5f=（4b/3-2d/3-10f/3）/(2b -d -5f)=2/3
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代入数字 自己随便设一个数字代入 目前求出第二题是1/9 过程等下打
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1.a/b =c/d =e/f = 1/3,
所以，3a=b,3c=d,3e=f,
a -2c +3e / b - 2d + 3f =1/3
2, x / 2 =y / 3 =z /4
所以,x=z/2,y=3z/4
x+y-z / x+y+z =1/9
3, a/ b =c/d =e/f =2/3
所以,3a=2b,3c=2d,3e=2f
a+c/b+d=3/2
2a-c-5e/2b -d -5f=2(2a-c-5e/6a-3c-15e)=2/3