1、已知x=2,y=-1是方程组3x+2y=m,nx-3y=5的解1已知x=2,y=-1是方程组3x+2y=m,nx-3y=5的解,则m=(),n=()2已知方程组3a-2b=16,2a+3b=2的解为a=4,b=-2则由3(x+y)-2(x+y)=16,2(x+y)+3(x-y)=2可得x+y=(),x-y=()3
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![1、已知x=2,y=-1是方程组3x+2y=m,nx-3y=5的解1已知x=2,y=-1是方程组3x+2y=m,nx-3y=5的解,则m=(),n=()2已知方程组3a-2b=16,2a+3b=2的解为a=4,b=-2则由3(x+y)-2(x+y)=16,2(x+y)+3(x-y)=2可得x+y=(),x-y=()3](/uploads/image/z/11558381-5-1.jpg?t=1%E3%80%81%E5%B7%B2%E7%9F%A5x%3D2%2Cy%3D-1%E6%98%AF%E6%96%B9%E7%A8%8B%E7%BB%843x%2B2y%3Dm%2Cnx-3y%3D5%E7%9A%84%E8%A7%A31%E5%B7%B2%E7%9F%A5x%3D2%2Cy%3D-1%E6%98%AF%E6%96%B9%E7%A8%8B%E7%BB%843x%2B2y%3Dm%2Cnx-3y%3D5%E7%9A%84%E8%A7%A3%2C%E5%88%99m%3D%EF%BC%88%EF%BC%89%2Cn%3D%EF%BC%88%EF%BC%892%E5%B7%B2%E7%9F%A5%E6%96%B9%E7%A8%8B%E7%BB%843a-2b%3D16%2C2a%2B3b%3D2%E7%9A%84%E8%A7%A3%E4%B8%BAa%3D4%2Cb%3D-2%E5%88%99%E7%94%B13%28x%2By%EF%BC%89-2%EF%BC%88x%2By%EF%BC%89%3D16%2C2%EF%BC%88x%2By%EF%BC%89%2B3%EF%BC%88x-y%EF%BC%89%3D2%E5%8F%AF%E5%BE%97x%2By%3D%EF%BC%88%EF%BC%89%2Cx-y%3D%EF%BC%88%EF%BC%893)
1、已知x=2,y=-1是方程组3x+2y=m,nx-3y=5的解1已知x=2,y=-1是方程组3x+2y=m,nx-3y=5的解,则m=(),n=()2已知方程组3a-2b=16,2a+3b=2的解为a=4,b=-2则由3(x+y)-2(x+y)=16,2(x+y)+3(x-y)=2可得x+y=(),x-y=()3
1、已知x=2,y=-1是方程组3x+2y=m,nx-3y=5的解
1已知x=2,y=-1是方程组3x+2y=m,nx-3y=5的解,则m=(),n=()
2已知方程组3a-2b=16,2a+3b=2的解为a=4,b=-2则由3(x+y)-2(x+y)=16,2(x+y)+3(x-y)=2可得x+y=(),x-y=()
3甲乙丙三种货物,若购甲三件,乙七件,丙一件,共需63元;若购买甲4贱,乙10件,丙1件,共需84元,现购买甲乙丙各1件,共需()
要大概思路,
1、已知x=2,y=-1是方程组3x+2y=m,nx-3y=5的解1已知x=2,y=-1是方程组3x+2y=m,nx-3y=5的解,则m=(),n=()2已知方程组3a-2b=16,2a+3b=2的解为a=4,b=-2则由3(x+y)-2(x+y)=16,2(x+y)+3(x-y)=2可得x+y=(),x-y=()3
1,将xy的值代入方程,使方程变为以mn为未知数的二元一次方程,解之,m=4,n=1
2,首先我认为你的题目错了,应该是3(x+y)-2(x-y)=16
如果是我改后的题目,可将(x+y)整体看成a,(x-y)整体看成b,两个方程组就是一样的了,所以解相同,即(x+y)=4,(x-y)=-2
3,设甲乙丙的单价为abc
有 3a+7b+c=63 (1)
4a+10b+c=84 (2)
(2)*3-(1)*4:2b-c=0 (3)
(2)-(1):a+3b=21 (4)
(4)-(3):a+b+c=21
即为所求