x y=150 16乘2x=43y-搜答案-智慧作业帮

∵xy＋yz＋zx＝1≧3³√x²y\x05²z²∴xyz≦1/（3√3),记xyz＝A,即A≦1/（3√3),∴所求式≧3³√A/［8-4√3（x+

原式=4x²y³÷(-1/2xy)²=4x²y³÷[(-1/2)²x²y²]=4x²y³÷[(1/4

2x²+2y²=2(x²+y²)=2(x²+y²+2xy-2xy)=2(x²+y²+2xy)-4xy=2(x+y)

3x的平方乘y-[2x的平方乘y-(2xy的平方-x的平方乘z)-4x的平方乘z]-xyz,当x=2,y=3,z=1时,求值=3x²y-2x²y+2xy²-x²

括号应该成对,还有一个括号在哪里?能不能把你的叙述用数学的语言表达出来?

∵x^2+y^2-2x+4y+5=0配方：∴(x-1)^2+(y+2)^2=0那么x-1=0且y+2=0所以x=1,y=-2∴(x^4-y^4)/(2x^2+xy-y^2)*（2x-y)/(xy-y^

2x+y=0可得： y=-2x于是(x-2y)/(x²+xy)*(x²-y²)÷(x²-4xy+4y²)/x=(x-2y）/x(x+)*（x

（x-3)（y+2）=xy-3y+2x-6=xy推出2x-3y=6（x+1)(y-1）=xy-x+y-1=xy-6推出x-y=5解方程组,得：x=9;y=4.同学,要动脑哇!

X^2+Y^2=2XY=1/22X^2-Y^2-3XY-(X^2-2Y^2+XY)=2X^2-Y^2-3XY-X^2+2Y^2-XY=X^2+Y^2-4XY=2-4*1/2=2-2=0

x=3y再答：带入再答：3.5

(xy-x²)÷(x²-2xy+y²)/(x-y)×(x-y)/x²=-x(x-y)÷(x-y)²/x²=-x(x-y)×x²/(

因为x²+2y-根号2乘y=17+4根号2,所以x²+2y=17,-y=4解得y=-4,x²=25所以x=±5所以x-y=5-(-4)=9,或x-y=-5-(-4)=-5

2(x^2y+xy)-3(x^2y-xy)-4x^2y=2x^2y+2xy-3x^2y+3xy-4x^2y=-5x^2y+5xyx=1,y=-1=-5*1*(-1)+5(-1)*1=5-5=0

带入x=2,y=1,最后得出-4

x^2+4y^2-2x+8y+5=0吧(x-1)^2+4(y+1)^2=0x=1,y=-1（x的四次方-y的四次方）/（2x²+xy-y²）×（2x-y)/（xy-y²）

2x的立方乘y+4x的平方乘y的平方+2xy的立方=2xy(x²+2xy+y²)=2xy(x+y)²=2×2×4²=64

X²+2xy+y²/xy乘x²-2xy+y²/xy+y²=(x+y)²/xy×(x-y)²/y(x+y)=(x+y)(x-y)&#

[(x^4-y^4)/(x^2-2xy+y^2)]*(y-x)/(x^2+y^2)=[(x-y)(x+y)(x^2+y^2)/(x-y)^2]*(y-x)/(x^2+y^2)=[(x^2+y^2)(x

xy^2*(-x^2y^2)(1/2xy^3)^2=-xy^2*x^2y^2*1/4x^2y^6=-1/4x^5y^10(xy^2)^5=x^5y^10当xy^2=2时,原式=-1/4*2^5=-1/

2x^2y(-2xy^2)^3+(2xy)^3乘(-xy^2)^2=2x^2y×(-8x^3y^6)+8x^3y^3×x^2y^4=-18x^5y^7+8x^^5y^7=-10x^5y^7当x=4,y