x y=71,x-y=5,求Y和X
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xy/x+y=3则xy=3(x+y)2x-5xy+2y/x-3xy+y=2(x+y)-5xy/(x+y)-3xy=2(x+y)-15(x+y)/(x+y)-9(x+y)=-13(x+y)/-8(x+y
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!
依题意得,xy+(x+y)=71xy*(x+y)=880则xy,(x+y)为方程t^2-71t+880=0的两根.∴xy=55,x+y=16或xy=16,x+y=55∴x^2+y^2=(x+y)^2-
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)
原式=[4(x+y)-2xy]分之[(x+y)+xy]=[4(3xy)-2xy]分之[(3xy)+xy]=10xy分之2xy=5分之1
前两个式子相减:x-xy-(xy-y)=x+y-2xy=5-(-3)=8
参考不知道对不对x-y=6得x-y的平方=36x-y的平方等于x平方+y平方-2xy所以116--2xy=36所以-2xy=-80所以xy就等于40
x=-1,y=-6或x=6,y=1代入式子得x^2-xy^2=37或30x^2y+xy^2=-42或42
(x-xy)+(xy-y)=40-20x-xy+xy-y=20x-y=20(x-xy)-(xy-y)=40-(-20)x-xy-xy+y=60x+y-2xy=60
因为X+Y分之XY=2,所以XY=2(X+Y)代入后面的分子式得:13(X+Y)/5(X+Y)=13/5
(x+y):y=8:33x+3y=8y得3x=5y设x=5a,y=3a所以(2x+5y)/(3x-y)=(10a+15a)/(15a-3a)=25a/12a=25/12(x^2-xy)/(y^2+3x
x²+y²=19(x+y)²=x²+y²+2xy=25xy=3(x-y)*(x-y)=(x-y)²=x²+y²-2xy=
(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
xy/x+y=3xy=3(x+y)3x-5xy+3y/-x+3xy-y=3x-15(x+y)+3y/-x+9(x+y)-y=-12(x+y)/8(x+y)=-3/2
xy/(x+y)=2xy=2(x+y)(3x-5xy+3y)/(-x+2xy-y)=[3(x+y)-5xy]/[2xy-(x+y)]=[3(x+y)-10(x+y)]/[4(x+y)-(x+y)]=-
x+y=5xy(2x-3xy+2y)/(x+2xy+y)=[2(x+y)-3xy]/[(x+y)+2xy]=(2×5xy-3xy)/(5xy+2xy)=7xy/7xy=1再问:若x+1/x=3,求(x
(*^__^*)嘻嘻……自己慢慢想吧!用计算器算呗
x^2-xy与xy-y^2相比各个式子提取公因式(x-y)求得x/y=3/2两个等式相加就是x^2-y^2=100因式分解(x+y)*(x-y)=100将x=3y/2带入求得y的平方是20可以x的平方
x-y=(x-xy)+(xy-y)=40+(-20)=20x+y-2xy=(x-xy)-(xy-y)=60