已知 |x 2| | y 3|= 0,求-2又2分之一x-3分之5y xy的值
来源:学生作业帮助网 编辑:作业帮 时间:2024/04/29 10:42:58
公式是:x方+y方+Dx+Ey+F=0把(x1,y1)(x2,y2)(x3,y3)代进去可以算出D.E.F再把D.E.F代进x方+y方+Dx+Ey+F=0R=二分之一倍根号下(D方+E方-4F)圆心坐
x=log2(y)则X1+2X2+3X3=log2(y1)+2log2(y2)+3log2(y3)=log2(y1)+log2(y2^2)+log2(y3^3)=log2(y1y2^2y3^3)=1所
分2种情况:①当K<0时,y2>y1>y3②当K>0时,y3>y1>y2
∵y=-2/x在(负无穷,0)上是增函数∴当y1>y2>y3>0时,0>x1>x2>x3选C
用FindFit[]函数data={{x1,y1},{x2,y2},{x3,y3},{x4,y4}};FindFit[data,ax^b,{a,b},x]
x3+y3=100(x+y)(x^2-xy+y^2)=100因x+y=1所以x^2-xy+y^2=100(x+y)^2-3xy=1001-3xy=100xy=-33x^2+y^2=(x+y)^2-2x
∵y1=y2∴x1=-x2∴x1+x2=0
∵x+y+z=0,∴z=(-x-y)x^3+y^3+z^3=x^3+y^3-(x+y)^3=x^3+y^3-x^3-y^3-3x^2y-3xy^2=-3xy(x+y)=3xyz
因为:X3-Y3-Z3=3XYZ所以:X3+(-Y)3+(-Z)3-3X(-Y)(-Z)=0(X-Y-Z)(X2+Y2+Z2+XY+XZ-YZ)=0所以:1.X-Y-Z=02.X2+Y2+Z2+XY+
(x+y+z)²-(x²+y²+z²)=2(xy+yz+zx)=-1,xy+yz+zx=-1/2x3+y3+z3=3xyz+(x+y+z)(x²+y&
∵(x+y+z)(x²+y²+z²)=x³+y³+z³+x²(y+z)+y²(x+z)+z²(x+y)∴1*2
x2-x1=(b-a)/3y3-y1=2(y3-y2)=2(b-a)/4所以(y3-y1)/(x2-x1)=3/2
设x2=y3=z4=k,则x=2k,y=3k,z=4k,∵2x-3y+4z=22,∴4k-9k+16k=22,∴k=2,∴x+y-z=2k+3k-4k=k=2.
∵方程2x2-7xy+3y3=0有正整数解,∴△=49y2-24y3=y2(49-24y)≥0,且y>0,解得,0<y≤4924;∴y=1或y=2;①当y=1时,原方程化为2x2-7x+3=0,即(2
请想想直线方程通式y=kx+b三个点都在直线上,分别代入方程5=3k+b-------b=5-3k7=kx2+b-------kx2=7-5+3k=2+3k-----k=2----x2=4y3=-1k
7-5=2(x2-3),x2=4y3-5=2(-1-3),y3=-3
迷惑人?70/3
设x2=y3=z4=k,则x=2k,y=3k,z=4k,∴4x−3y+5z2x+3y=4×2k−3×3k+5×4k2×2k+3×3k=1913.故答案为:1913.
x²-x=7y²-y=7相减x²-x-y²+y=0(x+y)(x-y)=x-yx-y≠0约分x+y=1x²-x=7y²-y=7相加x&sup