x y=5,x-y=1,求x的平方加y的平方
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1/x+1/y=5(y+x)/xy=5x+y=5xy2x-3xy+2y/x+xy+y=2(x+y)-3xy/(x+y)+xy=10xy-3xy/5xy+xy=7xy/6xy=7/6如果本题有什么不明白
x-y=2xy3x-5xy-3y/x+xy-y=[3(x-y)-5xy]/[(x-y)+xy]=(6xy-5xy)/(2xy+xy)=1/31/x+1/y=4y+x=4xyx-5xy+y/2x+xy+
xy/x+y=3xy=3(x+y)3x-5xy+3y/-x+3xy-y=(3x+3y)-5*3(x+y)/[-x-y+3*3(x+y)]=-12(x+y)/8(x+y)=-3/2望采纳,谢谢!
1/x+1/y=5(x+y)/x*y=5x+y=5*x*yx+2xy+y=x+y+2xy=5xy+2xy=7xy2x-3xy+2y=10xy-3xy=7xy(x+2xy+y)/(2x-3xy+2y)=
1/x-1/y=3(Y-X)/XY=3Y-X=3XYX-Y=-3XY(x-2xy-y)/(5x+3xy-5y)=(-3XY-2XY)/(-15XY+3XY)=-5XY/-12XY=5/12
答:x+y=-1,xy=-2-5(x+y)+(x-y)+x(xy+y)=-5x-5y+x-y+xy(x+1)=-4x-6y+(-2)(x+1)=-4x-6y-2x-2=-6x-6y-2=-6(x+y)
5xy+4x+7y+6x-3xy-4xy+3y=5xy-3xy-4xy+4x+6x+7y+3y=(5-3-4)xy+(4+6)x+(7+3)y=-2xy+10x+10y=-2xy+10(x+y)因为x
1/x+1/y=5两边乘以xy得y+x=5xy∴x+y=5xy3x+4xy+3y/x+3xy+y=[3(x+y)+4xy]/[(x+y)+3xy]=(15xy+4xy)/(5xy+3xy)=19xy/
-5(x+y)+(x-y)+2(xy+y)=-5x-5y+x-y+2xy+2y=-4x-4y+2xy=-4(x+y)+2xy=-4×(-1)+2×(-2)=4+(-4)=0你有问题也可以在这里向我提问
(5x-xy+5y)/(3xy-x-y)=[5(x+y)-xy]/[3xy-(x+y)]=[5(x+y)-2(x+y)]/[6(x+y)-(x+y)]=1/2
解题方法:分子、分母同时除一个xy(y+xy-x)/(2x+7xy-2y)=[(y+xy-x)/xy]/[(2x+7xy-2y)/xy]=(1/x+1-1/y)/(2/y+7-2/x)=[(1/x-1
设1/x-1/y=t(5x+xy-5y)/(x-xy-y)=(1-5(1/x-1/y))/(-1-(1/x-1/y))=(5t-1)/(t+1)至于是1/x-1/y=3还是1/y-1/x=3都差不多
(y+xy-x)/(2x+7xy-2y)(分子、分母同除一个xy)=(1/x+1-1/y)/(2/y+7-2/x)=6/(-10+7)=-2
这道题目还是在考察韦达定理的运用用伟大定理求出xy的值再代入代数式否则是求不出来的(x+y)^2=x^2+y^2+2xy=1x^2+y^2=5(x-y)^2=5-2(-2)=9下面分两种情况讨论1x-
分子,分母同时除xy(3/y-5-3/x)/(-1/y+3+1/x)=(6-5)/(3-2)=1
(5x+xy-5y)/(x-xy-y)=(5/y+1-5/x)/(1/y-1-1/x)=(1-3)/(-1-3)=1/2
5x²+5xy+y²+2x+1=04x²+y²+4xy+2x+x²+1=0(2x+y)²+(x+1)²=0得{2x+y=0---①
得y-x=3xyx-y=-3xy原式=-15xy+2xy/-3xy-4xy=-13/-7=13/7
1/x+1/y=5(x+y)/xy=5x+y=5xy(3x-5xy+3y)/(x+xy+y)=(15xy-5xy)/(5xy+xy)=10/6=5/3
因为1/x+1/y=5y/xy+x/xy=5(x+y)/xy=5所以x+y=5xy所以(2x-3xy+2y)/(x+2xy+y)=[2(x+y)-3xy]/[(x+y)+2xy]=(2×5xy-3xy