如果x 2=y 3,那么7x平方
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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
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
原式=x2+1x2+2-2,=(x-1x)2+2,=9+2,=11.故选D.
x3+y3=(x+y)(x2-xy+y2),∴x2-xy+y2=10,∵x+y=10,∴x2+2xy+y2=100,∴2xy=100-(x2+y2),把xy=x2+y2-10,代入得:100-(x2+
x的平方+X+1=0方程式不成立
∵x2+2x=3∴x4+7x3+8x2-13x+15=x2(x2+2x)+5x3+8x2-13x+15=x2×3+5x3+8x2-13x+15=5x3+11x2-13x+15=5x(x2+2x)+x2
y^2=x^3-3x^2+2xx^2=y^3-3y^2+2y两式相减得:y^2-x^2=(x^3-y^3)-3(x^2-y^2)+2(x-y)(x-y)(x^2+xy+y^2-2x-2y+2)=0所以
由x2+x-1=0得x2+x=1,∴x3+2x2-7=x3+x2+x2-7,=x(x2+x)+x2-7,=x+x2-7,=1-7,=-6.故选C.
原方程可化为y+10/y=7y^2-7y+10=0(y-2)(y-5)=0y1=2,y2=5y1=x^2-3/x=2x^2-3=2xx^2-2x-3=0(x-3)(x+1)=0x1=3,x2=-1y2
设x1+y1=x2+y2=x3+y3=x4+y4=X5+y5=A,y1=A-x1,y2=A-x2,...,y5=A-x5.yˉ=(y1+y2+...+y5)/5=(A-x1+A-x2+...+A-x5
x^3+y^3=(x+y)(x^2-xy+y^2)=10(x^2+y^2-xy)=100x^2+y^2-xy=10(1)x+y=10平方x^2+2xy+y^2=100(2)(1)*2+(2)2x^2+
由题意得:x2-x=2-4x+4x2-10=4(x2-x)-10=-2故填-2.
x3-2x-7=x3+x2-x2+2x-7=(x3+x2-x)-(x2+x-1)-8=x(x2+x-1)-(x2+x-1)-8=-8
设x2=y3=z5=t,则x=2t,y=3t,z=5t,∴x+3y−zx−3y+z=2t+9t−5t2t−9t+5t=-3.故答案是:-3.再问:=v=O(∩_∩)O谢谢
根据题意,设x=2k,y=3k,z=4k∵x+y+z=18∴2k+3k+4k=18,解得k=2∴x=4,y=6,z=8∴x+y-z=2.
左边=x3-x2y+xy2+x2y-xy2+y3=x3+y3=右边
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