z=x3 y3-3(x² y²)求驻点与极值
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5x+3y=3z--------a-x-3y=-z--------ba式+b式4x=2z得z=2x代入a中得x=3y,y=x/3x:y:z=x:x/3:2x=1:1/3:2=3:1:6
x:y:z=(3y/5):y:(7y/4)=(3/5):1:(7/4)=12:20:35再问:已知x+2y-z=02x+3y+z=0求x:y
x=4y/3y=yz=2y/5所以,x:y:z=4/3:1:2/5=20:15:6
x/(y+z)=y/(x+z)=z/(x+y)当x+y+z=0时,x+y=-z(x+y)/z=-z/z=-1当x+y+z≠0时,由x/(y+z)=y/(x+z)=z/(x+y)根据等比性质可得(x+y
设x/3=y/4=z/5=k,则x=3ky=4kz=5k带入x+y+z/3x-2y+z,最后约去k就可以了
设x/3=y/4=z/5=m则x=3m,y=4m,z=5m则x+y+z/3x-2y+z=(3m+4m+5m)/(9m-8m+5m)=12/6=2
因为x:y:z=3:4:5所以设x=3k,y=4k,z=5k(k≠0)(1)z/(x+y)=5k/(3k+4k)=5k/7k=5/7(2)x+y+z=63k+4k+5k=612k=6k=1/2x=3k
x+y+z-6=02x+3y-z-12=02x-y-z=0组成方程组再解x=2y=3z=1
依题意得,3y=4x,所以y=4/3x,同理,z=5/4y=5/3x,代入得1
4x-3y-3z=0.1)x-3y+z=0.2)相减:3x=4zx/z=4/31)-2)*4:9y=7zy/z=7/9所以:x/z=4/3,y/z=7/9
4x-3y-3z=0(1)x-3y+z=0(2)(1)-(2):3x-4z=0x=4z/3代入(1):16z/3-3y-3z=0y=7z/9所以:x:z=4:3y:z=7:9
解二元一次方程X+Y-5Z=0,3X-3Y-Z=0,求X:y:z16Y-14X=0X:Y=7/8X=7k,Y=8kZ=3kX:y:z=7:8:3再问:O(∩_∩)O谢谢!恩·····可以再详细点,吗?
x+2y+3z=20.(1)x+3y+5z=31.(2)(1)*2-(2)得x+y+z=9
X=3K,Y=4K,Z=5K3X+2Y-4Z=189K+8K-20K=18K=-6X=-18,Y=-24,Z=-30X+Y+Z=-72
根号x-3+|y-2|+z^2=2z-1根号x-3+|y-2|+(z^2-2z+1)=0根号x-3+|y-2|+(z-1)^2=0由于数值开根号,绝对值和平方数均为大于等于0的数则上式要成立只有X-3
x^3+y^3+x^3y^3=12,x^3+y^3+x^3y^3+1=13,(x^3+1)(y^3+1)=13(x+1)(x^2-x+1)(y+1)(y^2-y+1)=13;x+y+xy=0,x+y+
3元一次方程,好像是初一的问题哦.根据前面两个等式可以得出x=3zy=z(平方)/32x+3y+4z=2*(3z)+3*(z方/3)+4z现在变成了一元二次方程,你应该会解吧.
两式相加,得3x-z=0可得z/x=5将z=5x代入1式13x-y=0得y/x=13所以x:y:z=1:13:5
x:y:z=20:15:63x=4y,x:y=4:3=20:152y=5z,y:z=5:2=15:6x:y:z=20:15:6
应该是3X=4Y,5Y=6Z吧?X+Y:Y+Z=[(4Y/3)+Y]:(Y+5Y/6)=14;11