2x分之一-x y分之一×(2x分之x y-x-y)=?
来源:学生作业帮助网 编辑:作业帮 时间:2024/09/21 16:34:09
|xy-2|与|y-1|互为相反数,即|xy-2|+|y-1|=0xy-2=0,y-1=0所以x=2,y=1从而原式=1×2分之1+2×3分之1+3×4分之1+.+2015×2016分之1=1-2分之
(x^2)/2+xy+(y^2)/2=1/2*(x^2+2xy+y^2)=(x+y)^2/2=1/2
由 1/X-1/Y=5,两边同乘 XY,得出Y-X=5XY,那么 分子 -X+XY+Y=6XY分母 2X+7XY-2Y=7XY-2(Y-X)=-3XY 得此分式的值为-再问:还有一题x+x分之一=
答:1/x+1/y=3(x-2xy+y)/(2x+xy+2y)分子分母同除以xy得:=(1/y-2+1/x)/(2/y+1+2/x)=(3-2)/(3*2+1)=1/7
xy(xy+1)+(xy+3)-2(x+y+1/2)-(x+y-1)^2=xy(xy+1)+(xy+1)+2-2(x+y)-1-[(x+y)^2-2(x+y)+1]=(xy+1)^2+2-2(x+y)
√xy+y分之一+√xy+x分之一=√xy(1/x+1/y)=√xy乘[(x+y)/xy]=√xy(x+y)再问:√xy(1/x+1/y)这一步怎样计算?再答:(1/x+1/y)1/x和1/y通分再问
-2,前提是xy都不为零再问:能说一下解题步骤吗?
x分之1-y分之1=4(xy)分之(y-x)=4y-x=4xyx-y=-4xy(x-2xy-y)分之(2x+xy-2y)=[(x-y)-2xy]分之[2(x-y)+xy]=(-4xy-2xy)分之(-
1/X-1/Y=4Y-X=4XY(2X+XY-2Y)/(X-2XY-Y)=[2(X-Y)+XY]/[(X-Y)-2XY]=7/6
1/2x²+xy+1/2y²=1/2(x²+2xy+y²)=1/2(x+y)²=1/2
|x-1|+|y+3|=0|x-1|≥0|y+3|≥0所以x-1=0,y+3=0x=1,y=-3原式=1/1*-3+1/3*-1+1/1*5+1/3*7+1/5*9+.+1/(2n-1)(2n+3)=
x+2y=11/x+1/y=(x+2y)/x+(x+2y)/y=3+2y/x+x/y>=3+2*√2
x分之一减y分之一等于2分之1所以xy分之y-xy分之x=2分之1,xy分之(y-x)=2分之1,y-x=2分之xy,x-y=负2分之xy,所以x减y分之xy=(负2分之xy)分之xy=-xy分之(2
因为1/x-1/y=3所以方程左边先通分得y/xy-x/xy=3即(y-x)/xy=3所以得y-x=3xy(这一步很关键,一会要用整体代入法)要求的分数的分子:x+xy-y=xy-3xy=-2xy(因
x+y=6两边同时平方得x²+2xy+y²=36把xy=-2代入上式得x²+y²=401/x²+1/y²=y²/(x²y
1/xy+1/(x+1)(y+1)+1/(x+2)(y+2)+…+1/(x+2010)(y+2010)=1/(1*2)+1/(2*3)+1/(3*4)+.+1/(2011*2012)=1/1-1/2+
因为(x+1/y)(y+1/x)=xy+1+1+1/xy=18+2=20所以y+1/x=20/5=4再问:哦再问:我没想到,,,,
1/x+1/y=(x+y)/xy=5x+y=5xy所以原式=[2(x+y)-3xy]÷[(x+y)+2xy]=[2(5xy)-3xy]÷[(5xy)+2xy]=7xy÷7xy=1再问:1/x+1/y=
x+2y=11/x+1/y=(1/x+1/y)(x+2y)=1+x/y+2y/x+2≥3+2√2X分之一加Y分之一的最小值3+2√2
选择题最好的方法:设X=2,Y=1或X=-2,Y=-1,则1/X+1/Y=1/2+1=1.5或1/X+1/Y=-(1/2+1)=-1.5