将方程2分之x y-4
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原式=(2x+y)/(5xy-6xy)×(1/2)(x+2y)=(x+y)/(-xy)×(1/2)(x+y)=(-xy)/(2x+2y)=(-xy)/2(x+y)=(1/2)×(-xy)/(x+y)当
=(2X/3Y)*(3X/4Y)*(4/xy)=(2x*3x*4)/(3y*4y*xy)=2x/(y^3)
因为x-y=4xy所以x-2xy-y=2xy2x+3xy-2y=11xyx-2xy-y分之2x+3xy-2y=5.5
这个不能约分,已经是最简了不能化简
可以先设xy=t原式=[4(t-1)^2-(t+2)(2-t)]/(1/4*t)=4(4t^2-8t+4-2t+t^2-4+2t)/t=4(5t^2-8t)/t=(20t-32)/t=20-32/t将
xy/(x+y)=51/x+1/y=1/5yz/(y+z)=7/21/y+1/z=2/7zx/(z+x)=41/x+1/z=1/4(xy+yz+zx)分之xyz=1/(1/x+1/y+1/z)=280
x平方+y平方+2xy分之x平方-4y平方除以x平方+xy分之2y+x=(x-2y)(x+2y)/(x+y)²·x(x+y)/(x+2y)=x(x-2y)/(x+y)
x分之2减去x+1分之x=1两边同乘以x(x+1),得2(x+1)-x²=x(x+1)2x²-x-2=0
X=-1,1,-2,4X(X*X-4XY+4Y*Y)=4X*(X-2Y)(X+2Y)4X*X(2X+1)(2X-1)
xy^-2xy+2y-4=xy(y-2)+2(y-2)=(xy+2)(y-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
[4(xy-1)^2-(xy+2)(2-xy)]除以4分之1xy=[4x^2乘以y^2-8xy+4-(4-x^2y^2)]除以4分之1xy=(4x^2乘以y^2-8xy+4-4+x^2y^2)除以4分
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
解(-3/4x²y-3/5xy²)(-2/3xy)²=(-3/4x²y-3/5xy²)(4/9x²y²)=-1/3x^4y
分离,有dy/(2-y)=2xdx,d(2-y)=-dy,所以-d(2-y)/(2-y)=2xdx,两边积分,有-ln|2-y|=x^2+C>=0,所以ln|2-y|=0,y=1或3,x=0,C=0
[(xy-2)(-xy-2)-4(xy-1)^2]除以(-xy)=[-x²y²+4-4(x²y²-2xy+1)]÷(-xy)=(-x²y²+
x=1x=3x=4/9x=-(3/2)x=5