高考问答蓝光cd用什么播放:初一数学题，跪求~~~~
来源：百度文库 编辑：高考问答 时间：2024/05/08 08:31:26
1.已知m/n=2,求(m+2n)/(3m-2)的值
2.已知2x-y=0,求(x^2-y^2)/(x^3+y^3)除以(x-y)^2/(x+y)^3的值
2.已知2x-y=0,求(x^2-y^2)/(x^3+y^3)除以(x-y)^2/(x+y)^3的值
1.已知m/n=2,求(m+2n)/(3m-2)的值
m=2n
[m+2n]/[3m-2n]=[2n+2n]/[6n-2n]=4n/4n=1
2.已知2x-y=0,求(x^2-y^2)/(x^3+y^3)除以(x-y)^2/(x+y)^3的值
y=2x
[x^2-y^2]/[x^3+y^3]=[x^2-4x^2]/[x^3+8x^3]=-3x^2/9x^3=-1/3x
[x-y]^2/[x+y]^3=x^2/8x^3=1/8x
(x^2-y^2)/(x^3+y^3)除以(x-y)^2/(x+y)^3的值=[-1/3x]/[1/8x]=-8/3
1
m/n=2 所以m=2n 代入原式
4n/(6n-2)
2
不会
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