x Y=16-搜答案-搜搜考试网

x的平方-xy=16.(1)xy-y的平方=-8.(2)(1)*4-(2)*3,得(4x的平方-4xy)-(3xy-3y的平方)=16*4-(-8)*34x的平方-7xy+3y的平方=64+24=88

1.2(Xy+Xy)-3(Xy-xy)-4Xy=2*2xy-0-4xy=4xy-4xy=02.1/2ab-5aC-(3acb)+(3aC-4aC)=1/2ab-5ac-3acb-ac=1/2ab-6a

∵xy/(a＋b)＝1/15∴a＋b＝15xy同理：b＋c＝17xya＋c＝16xy∴xy/(a＋b＋c)＝xy/[1/2(2a＋2b＋2c)]＝xy/[1/2(a＋b＋b＋c＋a＋c)]＝xy/[1

x^+2xy+y^+4=16(x+y)²=16-4=12(1)x^-2xy+y^=16(x-y)²=16(2)(1)-(2)2y*2x=-4xy=-1(3xy+6y^)+|x^-(

20再答：

已知2x-3*根号(xy)-2y=0(x>0),则x2+4xy-16y2除以2x2+xy-9y2的值是多少?2x-3*根号(xy)-2y=0(根号X-2根号Y)(2根号X+根号Y)=0根号X-2根号Y

xy'=y+xy的

xdy=(y+xy)dxdy/y=((1+x)/x)dxln|y|=ln|x|+x+cy=±e^(ln|x|+x+c)其中c是常数再问：真还不理解我们是选择题：y=cxe^xy=c+x-x^2y=cs

3xy-[2xy-2(xy-2分之3xy)+xy]+3xy=6xy-[2xy-2xy+3xy+xy)=6xy-4xy=2xy=2×3×3分之1=2

(3x^2+2xy)/xy-(2x^2-xy)/xy=(3x^2+2xy-2x^2+xy)/xy=(x^2+3xy)/xy=x(x+3y)/xy=(x+3y)/y

x+y=16,xy=55,解方程

x=55/y;代入一式,x*x-16*x+55=0;解二元一次方程——(x-5)*(x-11)=0;所以x=5、y=11或x=11、y=5

xy=-8,xy(x+y)=-16-8(x+y)=-16(x+y)=2(x+y)²=4x²+y²+2xy=4x²+y²=4-2xyx²+y&

89

①xy同非负时,2x-3√xy-2y=(2√x+√y)(√x-2√y)=0∴√x=2√y,x=4y②xy同负时,2x-3√xy-2y=[2√(-x)+√(-y)][√(-x)-2√(-y)]=0∴√(

x^2-10xy=-100,①y^2-3xy=-40.②①*2-②*5,2x^2-5xy-5y^2=0,x=(5土√65）y/4,③代入②,[1-3(5土√65）/4]y^2=-40,（取+号）y^2

把xy=6代入3x²y-6xy²+18y+6=18x-36y+18y+6=18x-18y+6=18*16+6=294(2001+20012001+200120012001）=200

2x-3√(xy)-2y=0(2√x+√y)(√x-2√y)=0因为x>0,xy≥0所以y≥02√x+√y>0所以√x-2√y=0,即x=4y(x^2+4xy-16y^2)/(x^2+xy-9y^2)

由xy+x=16,得x=16/(y+1)代入xy-x=8,得16y/(y+1)-16/(y+1)=8=>16(y-1)/(y+1)=8=>(y-1)/(y+1)=1/2移项,通分得y-3/2(y+1)

方程组相加xy=12相减x+y=8（8-y）y=12y=2或6x=6或2

xy*yx=2268

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

|X|=3,Y的平方=16,XY

∵y²=16∴y=±4∵|x|=3∴x=±3∵xy