已知x>2,求x x-2分之四的最小值
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x²-2x+1+y²-y+1/4=0(x-1)²+(y-1/2)²=0平方大于等于0,相加等于0,若有一个大于0,则另一个小于0,不成立.所以两个都等于0所以x
xxxx-xxx-5xx-7x+5=(xx-2x-1)(xx+x-2)-10x+3=-10x+3由xx-2x-1=0得x=1±√2所以,xxxx-xxx-7x+5=-7±10√2
设x/2=y/3=z/4=t则x=2t,y=3t,z=4t∴(x-y+2z)/(3x-y)【分子应该是x-y+2z】=(2t-3t+8t)/(6t-3t)=(7t)/(3t)=7/3再问:谢谢我这题写
已知二分之x=三分之y=四分之z∴y=3x/2;z=2x;3x-2y+z分之2x+y-z=(2x+y-z)/(3x-2y+z)=(2x+3x/2-2x)/(3x-3x+2x)=3x/2/2x=3/4
7183(x+x^-1)
四分之x+2-六分之2x-3=1去分母,同乘12,得3(x+2)-2(2x-3)=13x+6-4x+6=xx=11又与mx+2m+6=0的解相同11m+2m+6=013m=-6m=-6/13
由已知方程可得:X^2=4X-1然后将分式中的X平方换成4X-1X的四次方换成X平方的平方再整理再将整理后的X平方继续换成4X-1最后化简:分子为4X-1分母为15(4X-1)得答案1/15这个题主要
三分之X=四分之Y=五分之Zx:y:z=3:4:5设x=3ay=4az=5a(x+y)/(x-2y+3z)=(3a+4a)/(3a-8a+15a)=7a/10a=7/10
xx+8x+16=(x+4)^2>=0x-y+1的绝对值>=0所以xx+8x+16=(x+4)^2=0x=-4y=-3xx+2xy+yy=49
解题思路::∵2x²+3x=82∴-2(2x²+3x)=(-2)×82即-4x²-6x=-164∴-4x²-6x+9=-164+9=-155解题过程:解:∵2x²+3x=82∴
2/9再问:过程,谢谢再答:由题目得y/x=2/3xy/xx+yy-yy/xx-yy=y/x-(y/x)²=2/3-4/9=2/9
x/(xx+x+1)=a分子分母除以x,1/(x+1+1/x)=a,x+1/x=1/a-1,两边平方xx+2+1/xx=(1/a-1)^2xx+1/xx=(1/a-1)^2-2xx/(xxxx+xx+
x+y=10x-y=8/7原式=-7³/8*(x+y)³*(x-y)*4(x+y)²(x-u)²=-343/2*(x+y)^5*(x-y)³=-343
xx+yy+4x-6y+13=0整理得:(x+2)^2+(y-3)^2=0那么只有(x+2)=0(y-3)=0x=-2y=3(x^2-2x)/(x^2+3y^2)=(4+4)/(4+3*9)=8/31
x^2+x-x^2-y=3x-y=3(x-y)^2=9x^2+y^2-2xy=9(x^2+y^2)/2-xy=9/2
17π/12<x<7π/4,得5π/3<x+π/4<2πcos(x-π/4)=cos[(x+π/4)-π/2]=sin(x+π/4)=-√[1-sin²(x+π/4)]=-√[1-(3/5)
x^2-2x+y^2+6y+10=0(x-1)^2+(y+3)^2=0所以x=1,y=-3x+y=-2x^2表示x的平方
x(x+1)-(xx+y)=-3x^2+x-x^2-y=-3x-y=-3(xx+yy)/2-xy=(x^2+y^2-2xy)/2=(x-y)^2/2=(-3)^2/2=9/2再问:是对的吧!再答:当然