已知x加4y等于5
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x的平方-4x+y的平方+2y+5=x的平方-4x+4+y的平方+2y+1=(x-2)^2+(y+1)^2=0x-2=0x=2y+1=0y=-1x+y=2-1=1
X+Y=5,XY=2,5X+4Y-3X-2Y+XY=2X+2Y+XY=2(X+Y)+XY=2×5+2=12.
已知x方加y方减2x加4y等于-5x方+y方-2x+4y+5=0x方-2x+1+y方+4y+4=0(x-1)方+(y+2)方=0所以x-1=0,y+2=0所以x=1,y=-2如果不懂,请追问,祝学习愉
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根据题意知:X/3=Y/4=Z/5设X/3=Y/4=Z/5=K则X=3K,Y=4K,Z=5K所以(X+Y)/(X-2Y+3Z)=(3K+4K)/(3K-2*4K+3*5K)=7K/(10K)=7/10
X-5=0,X=5,Y+4=0.Y=-4,X+Y=1,1的2006次=1
x^2+y^2+2x-4y+5=0,(x+1)^2+(y-2)^2=0,x=-1,y=2(-1)^2006-1/2=1-1/2=1/2
x的平方加y的平方加4x减2y加5等于0(x+2)^2+(y-1)^2=0x+2=0y-1=0x=-2y=1
通分原式=[(√x)²+(√y)²]/(√x*√y)=(x+y)/√(xy)=5/√4=5/2
X=5-YY=5-X再问:请问这叫什么公式呀?
x方+y方+5/4=2x+y(x方-2x+1)+(y方-y+1/4)=0(x-1)方+(y-1/2)方=0x=1,y=1/2xy/(x+y)=1/3
x²+y²-4x-2y+5=0x²-4x+4+y²-2y+1=0(x-2)²+(y-1)²=0x-2=0x=2y-1=0y=1√(x+y)/
x^2+4x+y^2-2y+5=0(x^2+4x+4)+(y^2-2y+1)=0(x+2)^2+(y-1)^2=0x=-2,y=1x^2+y^2=(-2)^2+1^2=4+1=5
x/3=y/4=z/5x=3/4y,z=5/4y(x+y-z)/(x-y+z)=(3/4y+y-5/4y)/(3/4y-y+5/4y)=1/2y/y=1/2
首先分母有理化,上下同乘以根号x加根号y,然后变成了(x+2乘以根号下xy+y)/(x-y)对xy=4开平方,得到根号下xy=2,(x-y)^2=(x+y)^2-4xy=9,你再开一下方就可以了得到(
由已知得(X-2)^2+(2Y+1)^2=0则X=2,Y=-1/2代入计算即可(后面的表达式看不大清楚)
2X+4Y=13①4X+3Y=11②①×2-②,得5Y=15Y=3带入①,得X=0.5
根据(x+y)2=x2+y2+2xy,可得x2+y2=13