2分之x y 3分之x-y=6 4(x y)-5(x-y)=2方程组
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原式=[(x+2y)/(x+y)][xy/(x+2y)]÷[(x+y)/xy]=[xy/(x+y)]×xy/(x+y)=x²y²/(x+y)²
(x的平方-y的平方)分之2xy+(x+y)分之x-(y-x)分之y=(x的平方-y的平方)分之2xy+(x+y)分之x+(x-y)分之y=(x²-y²)分之[2xy+x(x-y)
(x分之x-y)-(y分之x+y)+(2xy分之x的平方-y的平方)=1-y/x-1-x/y+(x^2-y^2)/2xy=-2(y^2+x^2)/2xy+(x^2-y^2)/2xy=-(x^2+3y^
(2X)/3+(3Y)/4=1/5(5X)/6-(5Y)/2=2(2X)*4+(3Y)*3=12/5(5X)-(5Y)*3=1240*X+45*Y=125*X-15*Y=1215*X-45*Y=365
1x^2y分之x^4=x²/y2ab分之ab-b^2(b不等于0)=1-b/a36abc^2分之36ab^3c=6b²/c4a^2-b^2分之(a+b)^3=(a+b)²
2:=19y或12(2/3)x或19(3/4)z3:④>②>③>①再问:过程再答:2:代入未知数一步步倒3:设极值a的绝对值=1那么a=1或者-1同理,b=2或者-2,那四个数每个数都把a,b代入其中
3)把①式乘以10,②式乘以6,得:25x+2y=-402x+y=1由下式得y=1-2x,代入上式得25x+2-4x=-4021x=-42x=-2则y=1+4=54)把①式乘以6,②式乘以2得3x-y
2.代入x、y得方程组:a+b+c=0(1)4a+2b+c=3(2)9a+3b+c=28(3)把(1)c=-a-b代入(2)(3),得3a+b=3(4)8a+2b=28(5)2*(4)-(5)得-2a
x3次方y-2x2y2+xy3=xy(x²-2xy+y²)=xy(x-y)²=3x3²=27如果本题有什么不明白可以追问,再问:=xy(x2-2xy+y2)=x
原式=[(x+2y)/(x+y)]×[xy/(x+2y)]÷[(x+y)/xy]=[(x+2y)/(x+y)]×[xy/(x+2y)]×[xy/(x+y)]=x²y²(x+2y)/
2x/(x²-64y²)-1/(x-8y)根据公式:a²-b²=(a+b)(a-b)=2x/(x+8y)(x-8y)-1/(x-8y)通分=2x/(x+8y)(
2x/3+3y/4=7/12(1)x/6-y/2=-1/3(2)(1)*12(2)*68x+9y=7(3)x-3y=-2(4)(4)*33x-9y=-6(5)(3)+(5)11x=1x=1/11将x=
x3y+xy3=xy(x^2+y^2)=(√3-√2)(√3+√2)((√3-√2)^2)+(√3-√2)^2)=1*(3-2√6+2+3+2√6+2)=10
题目没写完整,第二个等号,
是这样的形式吗?[x/(x+y)+2y/(x+y)]×[xy/(x+y)]÷(1/x+1/y)一:原式=(x+2y)/(x+y)×[xy/(x+2y)]÷[(x+y)/xy]=x²y&sup
x的平方-64y的平方分之2x-x-8y分之1=[2x-(x+8y)]/(x-8y)(x+8y)=(x-8y)/(x-8y)(x+8y)=1/(x+8y)
三分之X-Y+四分之X+Y=-2(1)六分之X-Y-八分之X+Y=3(2)(1)*1/2得六分之X-Y+八分之X+Y=-1(3)(2)+(3)得三分之X-Y=2,X-Y=6设Y=X-6(4)代入(1)
∵x-y=l,xy=2,∴x3y-2x2y2+xy3=xy(x2-2xy+y2)=xy(x-y)2=2×1=2.