2x-y=3则2x y=多少?
来源:学生作业帮助网 编辑:作业帮 时间:2024/10/03 04:24:18
你这道题是不是写错了?3y^3应该是3y^2?如果是的话,按照下面的去做2x^2-xy-3y^2=2(x^2+xy)-2xy-xy-3y^2=-2(x^2+xy)-3(y^2+xy)=2*3-3*(-
y-x=3xyx-y=-3xy(x-2xy-y)/(2x-14xy-2y)=(-3xy-2xy)/(-3xy*2-14xy)=-5xy/(-20xy)=1/4
-5x+2-3xy-5y因为xy=1所以原式=-5x-5y-1-5(x+y)-1因为x+y=3所以-15-1=-16
(x平方+2xy-3y平方)除以(x-y)=(x-y)(x+3y)/(x-y)=x+3y=12
x²y-xy²=xy(x-y)=3×2=6再问:怎样变为xy(x-y)再答:提取公因式x²y=(xy)×(x)xy²=(xy)×(y)都有因式xy,可以提取出来
k-2=0k=2
x²+xy=3两边同时乘以2得:2x²+2xy=6①xy+y²=-2两边同时乘以3得:3xy+3y²=-6②①-②得:2x²-xy-3y²=
1/x-1/y=3(y-x)/xy=3y-x=3xy(2x-14xy-2y)/(x-2xy-y)=[2(x-y)-14xy]/(x-y-2xy)=(-6xy-14xy)/(-3xy-2xy)=(-20
2(x+xy)-[(xy-3y)-x]-(-xy)=2x+2xy-xy+3y+x+xy=3x+3y+2xy=3(x+y)+2xy=3*(-2)+2*3=0
3x²-xy+y²=101-xy+4y²=421-2得3x²-3y²=6x²-y²=2选B
1/x-1/y=3则x-y=-3xyx-3xy-y/2x-xy-2y=(-3xy-3xy)/(-6xy-xy)=6/7
∵x-y=4xy,∴2x+3xy-2yx-2xy-y=2(x-y)+3xyx-y-2xy=8xy+3xy4xy-2xy=112.故答案为:112.
1/x-1/y=2(y-x)/xy=2y-x=2xy(3x+5xy-3y)/(x-xy-y)=[5xy-3(y-x)]/[-xy-(y-x)]=(5xy-6xy)/(-xy-2xy)=-xy/-3xy
x^2-3y^2=2xyx^2-2xy-3y^2=0(x-3y)(x+y)=0x=3y或者x=-y当x=3yx+2y=5yx-y=2y所以(x+2y)/(x-y)=5/2当x=-yx+2y=yx-y=
x²-y²=(2-xy)-(1-xy)=1
因为xy/(x+y)=1/2所以x+y=2xy原式=3(x+y)-5xy/(-x-y+3xy)=3*2xy-5xy/(-2xy+3xy)=xy/xy=1
若1/x-1/y=3,则2x+3xy-2y/x-xy-y=(2/y+3-2/x)/(1/y-1-1/x)=(3-2×3)/(-1-3)=-3/(-4)=3/4;很高兴为您解答,skyhunter002
xy/(x+y)=2(x+y)/xy=1/21/x+1/y=1/2(3x-xy+3y)/(-x+3xy-y)=(3/y-1+3/x)/(-1/y+3-1/x)=[3(1/x+1/y)-1]/[(3-(
∵x=2,y=3∴2(xy^2+3y^3-x^2y)-(-2x^2y+y^3+xy^2)-4y^3=2xy²+6y³-2x²y+2x²y-y³-xy&
是不是打错了?应该是x²+y²-3xy吧?(x+y)²=x²+2xy+y²=9①x²+y²-3xy=4②①-②得:x²+