若X-Y不等于0,2X-3Y=0-搜答案-百度作业网

2x^2-3xy+y^2=(2x-y)(x-y)=0则可得2x=y或x=y①当2x=y时把2x=y代入其中得x/y+y/x=x/2x+2x/x=1/2+2=2.5②当x=y时x/y+y/x=x/x+x

简单点是x=3y=4代入所求式子既可得或x=0.75y代入式子也可

30:3:5再问：稍微说一下理由谢谢!

=52X=3YX=3/2Y代入.(X+Y)/(X-Y)然后约份可得出=5

已知x-y≠0,x²-x=7,y²-y=7,求x³+y³+x²y+xy²的值.经观察可知,x、y相当于是方程t²-t=7的两个不等

X比Y=5比2正比例

因为x^2+xy-2y^2=0所以x=-2yx=y(1)x=-2y所以x/y-y/x-(x^2+y^2)/xy=-2+1/2+5/2=1(2)x=yx/y-y/x-(x^2+y^2)/xy=1-1-2

3X-3Y=2X+2YX=5YX/Y+Y/X=(XX+YY)/XY代入得26/5=5.2

X/X···这是什么意思···再问：x减y分之x等于x分之x减2y再答：两边同乘x（x-2y）再问：再答：题目是什么····就给个图啊···再问：如图，已知EFGH为矩形，AD⊥Bc于D，交HG于K，

2x-3y=0则：2x=3y令x=3k,y=2k则：原式=(6k-8k)/(3k-2k)=-2

(10x-11y)/(x-y)=[(8x-8y)+(2x-3y)]/(x-y)=8+(2x-3y)]/(x-y)=8+0=8

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=-

如果是(x-y)/x=x/x-2y,则x:y=2:3(x-y)/x=（x-2y+2y）/x-2y1-y/x=1+2y/(x-2y)-y/x=2y/(x-2y)x/y=(x-2y)/-2yx/y=-1/

=[(8x-8y)+(2x-3y)]/(x-y)=[(8x-8y)+0]/(x-y)=(8x-8y)/x-y=8(x-y)/x-y(这是乘法分配律)=8(约分同时除以x-y)

f'x(0,0)=lim(x→0)[f(x,0)-f(0,0)]/(x-0)=lim(x→0)x^3/x=lim(x→0)x^2=0由于F(x,y)={x^3-y^3/x^2+y^2在(x,y)→(0

2x-3y=02x=3y3x/y=9/2所以(3x-2y)/y=9/2-2=5/2

无解

2x=3y(y不等于0)x=3/2yx^2-y^2/2xy=(9/4y²-y²)÷(2×3/2y²)=5/4y²÷(3y²)=5/12

答：x^2-3x+1=0y^2-3y+1=0所以：x和y是方程a^2-3a+1=0的两个根根据韦达定理：x+y=3xy=1所以：(x+y)^2=9x^2+2xy+y^2=9所以：x^2+y^2=7所以

令a=x/2=y/3=z/4则x=2a,y=3a,z=4a所以原式=(2a+3a+4a)/(2a+3a-4a)=9a/a=9