x,y,z均是非负数,且满足:x 3y 2z=3,3x 3y z=4

x+y+z=30(1)3x+y-z=50(2)5x+4y+2z=m(3)(1)+(2)4x+2y=802x+y=40(4)(2)*2+(3)6x+2y+5x+4y=100+m11x+6y=100+m(

由两个等式相加可以得到：4x+2y=30=>y=15-2x>=0=>xxz=15+x>=0=>x>=-15则：u=5x+4*(15-2x)+2*(15+x)=90-x=>x=90-u由于x>=0且x再

X+2Y=1+Z2X+3Y=1+3Z解得X=3Z-1>=0Y=1-Z>=0Z>=01/3

x+y+z=30(一式).一式*3=3x+3y+3z=90(二式).二式减3x+y-z=50可得出2y+4z=40.所以y+2z=20.所以y=20-2z.所以把y=20-2z代入3x+y-z=50可

两式相加,有：4x+2y=80,即：y=40-2x代入：x+y+z=30得：z=x-10因为x、y、z是非负数,所以,x≥0y=40-2x≥0z=x-10≥0所以,10≤x≤20所以,w=5x+4y+

联立:X＋3Y＋2Z＝3,及3X+3y+Z＝4得:X=(1/2)+(Z/2)Y=(5/6)-(5Z/6)所以:m＝3X—2Y+4Z=(-1/6)+(43/6)ZZ为非负数,所以:m=(-1/6)+(4

x+3y+2z=3,x=3-3y-2z3x+3y+z=4,3(3-3y-2z)+3y+z=4,6y+5z=5,y=5/6-5z/6,故x=3-3y-2z=3-3(5/6-5z/6)-2z=1/2+z/

解x-1=1/2(y+1)=1/3(z-2)∴2(x-1)=y+1,3(x-1)=z-2∴y=2x-3,z=3x-1∴x²+y²+z²=x²+(2x-3)

题目直接输入百度,能找到相关信息~但方法是有的,答案还不一样!

题目"是非实数"应该是“是非负实数”吧.我们来点初级的解法：由x+3y+2z=3……①,3x+3y+z=4……②②-①得2x-z=1,z=2x-1≥0,所以x≥1/2②×2-①得5x+3y=5,y=3

x+2y-z=6,.(1)x-y+2z=3.(2)(1)-(2)y-z=1,y=1+z(1)+2(2)x+z=4,x=4-zx^2+y^2+z^2=(4-z)^2+(1+z)^2+z^2=3z^2-6

填空选择题快捷方式当且仅当x=y=z=4/3最大,得3x^2=16/3,解答题∵x^2+y^2≥2xy,x^2+z^2≥2xz,z^2+y^2≥2yz,得x^2+y^2+z^2≥xy+yz+xz,x^

∵x、y是正整数,且x^2＋z^2＝10,∴x^2＜10、且z^2＜10,∴x＜4、且z＜4.当x＝1时,有：1＋z^2＝10,∴z^2＝9,∴z＝3.当x＝2时,有：4＋z^2＝10,∴z^2＝6,

3y+2z=x+3,(1)3y+z=4-3x(2)(1)-(2)得：z=4x-1代入（2）得：y=(-7x+5)/3∴W=3x+y+z=3x+(-7x+5)/3+4x-1=14x/3+2/3∵x,y,

3(x-1)=2(2-y)3x-3=4-2yy=(7-3x)/2>=0x=0x>=-1/2所以0

8x+4y+2z=2(x+y+z)+2(3x+y-z)+2z=16+2z>=16,等号当x=1,y=2,z=0时取到；8x+4y+2z=3.5(x+y+z)+1.5(3x+y-z)-y=18-y

2X-2Z=20X=Z+10>=0Z>=0>=-10Y=20-2Z>=0Z

x+y+z+3x+y-z=80.解得y=40-2x,x+y+z-(3x+y-z)=-20,解得z=x-10,因为x,y,z均为非负数,则y=40-2x＞0,z=x-10＞0,x＞0.解得10＜x＜20

x+y+z+3x+y-z=80.解得y=40-2x,x+y+z-(3x+y-z)=-20,解得z=x-10,因为x,y,z均为非负数,则y=40-2x＞0,z=x-10＞0,x＞0.解得10＜x＜20

解前两个方程把X消掉求出Y=7-11Z因为Y≥0所以7-11ZY≥0所以Z≤7/11