已知x分之1减y分之1等于3
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1/x-1/y=3得y-x=3xy∴xy=(y-x)/3则x-xy-y=x-y-(y-x)/3=4(y-x)/35x+xy-5y=5(x-y)+(y-x)/3=14(x-y)/3∴(5x+xy-5y)
1/x-1/y=2y-x=2xyx-y=-2xy(3x+7xy-3y)/(2x-3xy-2y)=[3(x-y)+7xy]/[2(x-y)-3xy]=[-6xy+7xy]/[-4xy-3xy]=xy/[
再问:2/5再答:?
x/2=y/3=z/4=tx=2ty=3tz=4tx+y-z=1/122t+3t-4t=t=1/12x=1/6y=1/4z=1/3xyz=1/6*1/4/*1/3=1/72
直接设X=1,Y=0.5.带入后式得出10
1/x-1/y=4(y-x)/xy=4x-y=-4xy(3X+5xy-3y)/(x-3xy-y)=[3(x-y)+5xy]/[(x-y)-3xy]=(-12xy+5xy)/(-4xy-3xy)=1
得xy分之y-x=3得y-x=3xy带入得-9xy-5xy分之-3xy-2xy得14分之5..求采纳.谢谢
此题简单做法你直接可以设X=1,Y=0.5,使其满足前面的条件即可,带入后面分式,后面的式子中文表述不清,
1/x-1/y=(y-x)/xy=3y-x=3xy(2x-5xy-2y)/(3x-10xy-3y)=-8xy/-19xy=8/19自己算一下直接看着算的反正就是整体代入思想
由椭圆方程可知,a^2=4,b^2=3,所以c^2=1,所以焦点坐标是(c,0),(-c,0),即(-1,0)和(1,0),焦距=2x^2=1/4y类比x^2=2py焦点坐标(0,1/16),准线方程
y分之x减y=x/y-1=3/4-1=-1/4有什么不明白可以对该题继续追问请及时选为满意答案,
1/x-1/y=3y-x=3xyx-y=-3xy(5x-xy-5y)/(x-xy-y)=(-15xy-xy)/(-3xy-xy)=4
x分之1减y分之1等于31/x-1/y=3(y-x)/xy=3y-x=3xy所以x-xy-y分之5x-xy-5y=(-3xy-xy)分之(-15xy-xy)=-4分之(-16)=4
3/4x=y/5,则x:y=4:15,y/5=z/6,则y:z=5:6,所以:x:y:z=4:15:18
由已知条件可得:x-y=-4xy,(也就是在等式两边乘xy后整理,即可),代入所求的式子里分母为-4xy+7xy,即3xy;分子为-4xy-2xy,即-6xy,化简得-2
x/3=y/4=z/5x:Y:Z=3;4;5
x-2xy-y分之2x-3xy-2y=(2x-3xy-2y)/(x-2xy-y)分子分母同时除以xy=(2/y-3-2/x)/(1/y-2-1/x)=[-3-2(1/x-1/y)]/[-2-(1/x-
1/x+1/y=-1/(x+y)两边同时乘x+y得1+y/x+1+x/y=-1所以y/x+x/y=-3