已知x方 y方-4x-6y 13=0,求根号下三分之x
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x^2+4x+4+y^2-6y+9=0(x+2)^2+(y-3)^2=0x+2=0y-3=0x+y=1
X^2+6X+9+Y^2-8Y+16=0所以(X+3)^2+(Y-4)^2=0所以X=-3,Y=4所以(X+Y)^2-(X-Y)^2=4XY=4*4*(-3)=-48
因为3x方+xy-2y方=0,即(x+y)(3x-2y)=0,而x+y≠0,所以3x-2y=0原式=[(x+y)^2-4xy]/[(x+3y)(x-y)/(x+3y)(x-3y)=(x-3y)/(x+
x方+4y方=4xyx²-4xy+4y²=0(x-2y)²=0x=2yx+2y/x=(2y+2y)/(2y)=2
即(3x-4y)(x+y)=03x=4y或x=-y若3x=4yy=3x/4则y²=9x²/16,xy=3x²/4原式=(3x²/4-3x²)/(9x&
∵y/x=3∴y=3x∴原式=(3x²-12x²+18x²)/(6x²-3x*3x+7*9x²)=9x²/(60x²)=3/20
2(x+y)方-2=50-2=48
[(x²+y²)-(x-y)²+2y(x-y)]/4y=1[x²+y²-(x²-2xy+y²)+2xy-2y²]/4y=
x+y=15两边平方x²+2xy+y²=225所以2xy=225-(x²+y²)=12xy=6所以原式=113-6=107
先转化到2个未知数用另外一个未知数表示,然后代入求值4x-3y-6z=0x+2y-7z=0解得x=3zy=2z(2x²+3y²+6z²)/(x²+5y²
∵y分之x=5∴x=5y(4x²-5xy-6y²)分之(x²-2xy+3y²)=(100y²-25y²-6y²)分之(25y
等于-1或5解那式子可得(x-5y)(y+x)=0得x=5y或x=-y
8x^2-6y^2=146x^2+4y^2=3814x^2-2y^2=52
是这样的,x+y=5,x方加y方=13,所以可以求得xy,就是(x+y)的平方等于25,也就是x方+2xy+y方等于25,再用这个试子减x方+y方,剩下2xy=12,代数式x方y+2x方y方+xy方,
已知代数式9-6y-4y二次方=7,求2y二次方+3y+7=8,前面这不用求了吧.14x+5-21x二次方=-2,所以21x^2-14x=5,3x^2-2x=5/76x的二次方-4x+5=6x^2-4
6已知x+y=2,x-y=1,求分式x方+2xy+y方分之x方-y方的值x方+2xy+y方分之x方-y方=(x+y)(x-y)/(x+y)²=(x-y)/(x+y)=1/27已知x分之1-y
令y-x=ky=x+k代入圆方程,得x平方+(x+k)平方-4x+1=02x平方+(2k-4)x+k平方+1=0因为最大,所以△=(2k-4)平方-4×2×(k平方+1)=04k平方-16k+16-8
已知x方-4x+4+|y+x|=0,===>(X-2)^2+ly+xl=0====>x=2,y=-2,代入求解即可.(平方数>=0,绝对值>=0)再问:我问一下你的======是什么意思?你能帮我把过
∵x²+y²+6x-2y+10=0∴(x²+6x+9)+(y²-2y+1)=0即(x+3)²+(y-1)²=0由平方的非负性可得(x+3)&
=x^2+4xy+4y^2+y^2+6y+9=0(x+2y)^2+(y+3)^2=0x+2y=0,y+3=0x=6,y=-3x^2-y^2=6^2-(-3)^2=27