4x方减3y方等于7求x
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(x²+y²-3)(2x²+2y²-4)=242(x²+y²-3)(x²+y²-2)=24(x²+y²
(x-2)²+(y-3)²=1x=2+cosay=3+sinax²+y²=6sina+4cosa+14=√(6²+4²)sin(a+b)+1
已知x方加y方减2x加4y等于-5x方+y方-2x+4y+5=0x方-2x+1+y方+4y+4=0(x-1)方+(y+2)方=0所以x-1=0,y+2=0所以x=1,y=-2如果不懂,请追问,祝学习愉
x+y=7x^2+y^2=55(x+y)^2=x^2+y^2+2xy=492xy=49-55=-6,xy=-3(x^3)·(y^3)=(xy)^3=(-3)^3=-27
x^2=y+4,所以x^2-y=4y^2=x+4,所以y^2-x=4x^3-2xy+y^3=(x^3-xy)+(y^3-xy)=x(x^2-y)+y(y^-x)=4x+4yx^2=y+4,y^2=x+
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+
这是道线形规划的题可化为(x-2)^2+(y+4)^2=20可行域为一个圆然后设2x+3y=t则y=-2/3x+t/3斜率已有,画下图,算相切时的临界值,此时t的值即为最值不懂可以再追问~再问:麻烦写
∵y/x=3∴y=3x∴原式=(3x²-12x²+18x²)/(6x²-3x*3x+7*9x²)=9x²/(60x²)=3/20
已知x+y=1,则x^3+y^3+3xy=(x+y)(x^2-xy+y^2)+3xy=1×(x^2-xy+y^2)+3xy=x^2-xy+y^2+3xy=x^2+2xy+y^2=(x+y)^2=1^2
解1/x-1/y=7(y-x)/xy=7y-x=7xy∴(x²+y²)/xy=[(x-y)²+2xy]/xy=[(y-x)²+2xy]xy=(49xy+2xy)
x/y=-2则x=-2y则原式=(x²-2xy-3y²)/(x²-6xy-7y²)=(x+y)(x-3y)/(x+y)(x-7y)=(x-3y)/(x-7y)=
直接将二式相乘,得(x²+ax+b)(3x+1)=3x³+x²+3ax²+ax+3bx+b=3x³+(1+3a)x²+(a+3b)x+b由于
X+Y=7(X+Y)^2=49X^2+Y^2+2XY=49XY=12(X-Y)^2=X^2+Y^2-2XY=25-2*12=1所以X-Y=1
X^2+y^2=4求式=x^2-2√3-y^2=x^2-2√3-4+x^2=2x^2-2√3-4而x^2≤4则X^2=4时,原式最大为-2√3
x^2+y^2=4,设x=2cosa,y=2sina,则x^2-2√3xy-y^2=4(cosa)^2-8√3cosasina-4(sina)^2=4cos2a-4√3sin2a=8cos(2a+60
(x+y)/(x)=31+(y/x)=3得:y/x=2则:(x²+y²)/(x²-xy+y²)【分子分母同除以x²】=[1+(y/x)²]/
8x^2-6y^2=146x^2+4y^2=3814x^2-2y^2=52
x^2-xy=14xy-3y^2=2求x^2+3xy-3y^2因为x^2-xy=1所以x^2=1+xy带入原式得4xy+1-3y^2因为4xy-3y^2=2将其带入原式得2+1=3