若方程组{4x 3y=1 mx (1-m)y=3的解x和y互为相反数,则m的值为
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解方程组:x+y=3x-y=1得;x=2,y=1把x=2,y=1代入二元一次方程组mx+ny=8mx-ny=4即:2m+n=82m-n=4解得:m=3n=2
由题目意思联立方程4x-y=7,3x+2y=8解得x=2,y=1再把它们代入mx+ny=1,2mx+3ny=17得2m+n=1,4m+3n=17解得m=-8,n=15
依题意m+n=7-mm-n=n+1m=3,n=13x+2y=5,3x-y=1x=7/9,y=4/3
原式=(x4-xy3)+(y4-x3y)+(3xy2-3x2y)=x(x3-y3)+y(y3-x3)+3xy(y-x)=(x3-y3)(x-y)-3xy(x-y)=(x-y)(x3-y3-3xy)=(
联立方程:4x+3y=22,(1)x=2y(2)(2)带入(1)得y=2进一步解得x=4把x=4,y=2带入mx+(m-3)y=3:4m+2(m-3)=36m=9m=3/2
原式=x4+x3y+4x3y+x2y+4x2y2+4x2y2+xy2+4xy3+xy3+y4,=x3(x+y)+4x2y(x+y)+xy(x+y)+4xy2(x+y)+y3(x+y),=-x3-4x2
(2x4-4x3y-x2y2)-2(x4-2x3y-y3)+x2y2=2x4-4x3y-x2y2-2x4+4x3y+2y3+x2y2=2y3,因为化简的结果中不含x,所以原式的值与x值无关.
原式=(x^4-2x²y²+y^4)+6xy(x²+2xy+y²)-2xy(x+y)=(x²-y²)²+6xy(x+y)²
由2x-y=1得,y=2x-1,代入mx-3y=9得,mx-3(2x-1)=9,整理得,(m-6)x=6,所以m=6时,原方程组无解.故选B.
x=1.5m-2①y=1.5-0.5x=1.5-0.75m+1=2.5-0.75m②带入mx-y=2得:1.5m^2-2m+0.75m-2.5=26m^2-5m-18=0解得:两个m值分别带入①②求出
∵|x+y+1|≥0,|xy-3|≥0|x+y+1|+|xy-3|=0,∴x+y+1=0,即x+y=-1xy=3xy3+x3y=xy(x²+y²)=yx[(x+y)²-2
5x=1x=1/5y=1/51/5m+m+2=4m=5/3
先把x=4,y=2代入到原方程组,得,4m+2n=-8,(1)4m-2n=5(2),甲看错了方程(1)中的m,但没看错n,消去m,解得,n=-13/4先把x=2,y=5代入到原方程组,得,2m+5n=
x+y=3,x-y=1两式相加2x=4x=2代入第一式y=1将x=2,y=1代入mx+ny=3,mx-ny=52m+1n=3,2m-1n=5两式相加4m=8m=2代入2m+n=3n=-1
甲的解满足第二个方程,所以4m-2n=5.乙的解满足第一个方程,所以2m+5n=-8.解方程组4m-2n=5,2m+5n=-8.第二个方程乘以-2加到第一个方程,得-12n=5+16,所以n=-7/4
将X=4Y=2代入mx-nx=8(2).将X=2Y=5代入mx+ny=-8(1),组成新的方程组,再问:要过程再答:对甲来说,看错了方程(1)中的m,得到的解是X=4Y=2,这个解对方程mx-nx=8
x4-xy3-x3y-3x2y+3xy2+y4=(x4-xy3)+(y4-x3y)+(3xy2-3x2y)=x(x3-y3)+y(y3-x3)+3xy(y-x)=(x3-y3)(x-y)-3xy(x-
a1=a2,b1=-b2,c1=c2a1=a2,b1=b2,c1不等于c2a1不等于a2,b1不等于b2,c1不等于c2
即y=-x代入4x+3y=14x-3x=1x=1y=-1所以m--(1-m)=3m-1+m=3m=2