如果2X等于3y那么2x y杠2x-y等于多少-搜答案-大师作文网

=2+7=9再问：x等于多少，y等于多少（要过程再答：x^2+xy=2=>x(x+y)=2xy++y^2=7=>y(x+y)=7上面两式相加即可得出x^2+2xy+y^2=9。=>x+y=-3或者3代

xy/(x+y)=2∴xy=2(x+y)(3xy-x-y)/(3x-5xy+3y)=[6(x+y)-x-y]/[3x+3y-10(x+y)]=5(x+y)/[-7(x+y)]=-5/7

x+y=2,y=2-x,xy=x(2-x)若x=0,2,xy=0若2>x>0,2>xy>0x2,xy

x-y=6（1）,xy=7,（2）由（1）得y=6+x（3）把（3）带入（2）的x（6+x）=7解得x=1或者x=-7x=1时y=7或者x=-7时y=1x^2-y^2=-48或者48

x的平方+3xy+2y的平方=（x的平方+xy）+（xy+y的平方）+（xy+y的平方）=3-2-2=-1

A-[B-(-2B+A]=A-(B+2B-A)=A-3B+A=2A-3B=2(3X²-XY+Y²)-3(2X²-3XY-2Y²)=6X²-2XY+2Y

你传错了吧,怎么无解啊~

x²＋xy＝3………………………①y²＋xy＝－2……………………②①＋②得：x²＋2xy＋y²＝1（x＋y）²＝1x＋y＝±1∴x²＋3x

如果问题写清楚一些就好啦

1/3x²+2/3xy+1/3y²=1/3(x²+2xy+y²)=1/3(x+y)²=1/3×(-6)²=1/3×36=12很高兴为您解答,

你先设x/y=k,即x=yk所以原式=3k^2y^2+ky^2-4y^2=0即y^2(3k^2+k-4)=0因为y不能等于0,所以^2不等于0即3k^2+k-4=0得k=1(x不等于y,舍去）,K=-

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

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+2xy+y^2=(x^2+xy)+(xy+y^2)=2+7=9

x^2+2xy+y^2=(x^2+xy)+(xy+y^2)=2+7=9

2A—3B=2(3x^2-xy+y^2)-3(2x^2-3xy-2y^2)=6x^2-2xy+2y^2-6x^2+9xy+6y^2=7xy+8y^2

2x+3y-3xy+4xy-3x-4y+7=(2x-3x+3y-4y)+4xy-3xy+7=(-x-y)+xy+7=-(x+y)+xy+7=-4-1+7=2

2A-3B=2(3x²-xy+y²)-3(2x²－3xy－2y²)=6x²-2xy+2y²-6x²+9xy+6y²=7x

∵x3y2+x2y3=x2y2（x+y），而x+y=-3，xy=-2，∴x3y2+x2y3=4×（-3）=-12．故答案为：-12．