1.方程组x+y=m,2x-y=6中x,y的和为正数,x与y的差为负数求m的取值范围.2.方程组4x+3m=2,8x-3y=m的解满足x>y则m满足________(这2个题要步骤)
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![1.方程组x+y=m,2x-y=6中x,y的和为正数,x与y的差为负数求m的取值范围.2.方程组4x+3m=2,8x-3y=m的解满足x>y则m满足________(这2个题要步骤)](/uploads/image/z/8857642-58-2.jpg?t=1.%E6%96%B9%E7%A8%8B%E7%BB%84x%2By%3Dm%2C2x-y%3D6%E4%B8%ADx%2Cy%E7%9A%84%E5%92%8C%E4%B8%BA%E6%AD%A3%E6%95%B0%2Cx%E4%B8%8Ey%E7%9A%84%E5%B7%AE%E4%B8%BA%E8%B4%9F%E6%95%B0%E6%B1%82m%E7%9A%84%E5%8F%96%E5%80%BC%E8%8C%83%E5%9B%B4.2.%E6%96%B9%E7%A8%8B%E7%BB%844x%2B3m%3D2%2C8x-3y%3Dm%E7%9A%84%E8%A7%A3%E6%BB%A1%E8%B6%B3x%3Ey%E5%88%99m%E6%BB%A1%E8%B6%B3________%28%E8%BF%992%E4%B8%AA%E9%A2%98%E8%A6%81%E6%AD%A5%E9%AA%A4%EF%BC%89)
1.方程组x+y=m,2x-y=6中x,y的和为正数,x与y的差为负数求m的取值范围.2.方程组4x+3m=2,8x-3y=m的解满足x>y则m满足________(这2个题要步骤)
1.
方程组x+y=m,2x-y=6中x,y的和为正数,x与y的差为负数求m的取值范围.
2.方程组4x+3m=2,8x-3y=m的解满足x>y则m满足________
(这2个题要步骤)
1.方程组x+y=m,2x-y=6中x,y的和为正数,x与y的差为负数求m的取值范围.2.方程组4x+3m=2,8x-3y=m的解满足x>y则m满足________(这2个题要步骤)
1x,y的和为正数,则m>0
x+y=m,2x-y=6得x=(m+6)/3,y=(2m-6)/3
x与y的差为负数,则(m+6)/3-(2m-6)/3小于0
即m>12
所以m>12
2 4x+3m=2,8x-3y=m得出x=(2-3m)/4,y=(4-7m)/3
x>y则(2-3m)/4>(4-7m)/3
得出m>19/10
g
第二题
4x+3m=2,x=(2-3m)/4
8x-3y=m,y=(8x-m)/3,将x的方程代入,得:y=(4-7m)/3
由x>y得:6-9m>16-28m,m>10/19
1.因为x-y<0
y-x>0,y+x>0
y>0
x=m-y
2(m-y)-y=6
y=(2m-6)/3>0
m>3
2.因为5/4*(4x+3m)=5/4*3....①
8x-3y=m....②
②-①得(x-y)=5/4(1-m)
因为x-y>0
5/4(1-m)>0
m<1
1、由2x-y=6得x=(6+y)/2代入x-y<0得y>6,再由x+y=m得3+(3y/2)=m得m>12
2、由x>y与8x-3y=m得m>5x由4x+3m=2得m=(2-4x)/3得x<2/19得m>10/19