x y-20=2 3(y x-10)
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yx+xy=xyx+xyy=xy(x+y)xy,∵x+y=8,xy=6,∴原式=6×86=463.
[2x(x²y-xy²)+xy(xy-x²)]/x²y=[2x^3y-2x^2y^2+x^2y^2-x^3y]/x²y=x-y=4
∵x+y=4,xy=3,∴原式=x2+y2xy=(x+y)2−2xyxy=16−63=103.
X=9Y=1Z=091+19=110X+Y+Z=10
由于x-y=a,z-y=10得x-z=a-10并且由x²+y²+z²-xy-yx-zx=1/2[(x-y)²+(y-z)²+(z-x)²]=
∵1-8x≥0,8x-1≥0,∴x=18,y=12,∴代数式xy+yx+2-xy+yx−2=14+4+2-14+4−2=52-32=1.故选:B.
=xy-3xy+2xy-xy=-xy
因为y=3xy+x,所以x-y=-3xy,当x-y=-3xy时,2x+3xy−2yx−2xy−y=2(x−y)+3xy(x−y)−2xy=2(−3xy)+3xy−3xy−2xy=35.
10x+y-(10y+x)=x9x-9y=x8x=9yx=9,y=8xy=98
直接就等于-5/4xy再答:xy=yx,乘法交换律再答:就相当于把xy看做一个整体,比如xy=a,那么-1/4a-1a等于多少呢的问题
xy+yx=10x+y+10y+x=11x+11y=100+x10x=100-11yx=10-1.1y所以y只能是0
∵x-y=4xy,∴2x+3xy-2yx-2xy-y=2(x-y)+3xyx-y-2xy=8xy+3xy4xy-2xy=112.故答案为:112.
乘法交换律,所以相等
根据题意,2x2-3xy+y2=0,且xy≠0,故有(yx)2−3yx+2=0,即(yx−1)(yx−2)=0,即得yx=1或2,故xy=1或12,所以xy+yx=2或212.故选A.
3xy-3xy-xy+2yx=-xy+2xy=xy
yx+xy=x2+y2xy=(x+y)2-2xyxy当x+y=2,xy=-5时,原式=22-2×(-5)-5=-145.故答案为-145.
XY=XZ+YX?那么也就是XY=X(Z+Y)咯,Y=Z+Y?无法证明的.题抄错啦~`
∵5x2-xy-6y2=0,∴(5x-6y)(x+y)=0,∴5x-6y=0,x+y=0,∴5x=6y,x=-y,∴yx=56或-1.故答案为:56或-1.
即(10x+y)*(10y+x)=2268101xy+10x²+10y²=2268因为后面的10x²+10y²只可能是整十的数,所以2268中的个位8要靠101