作业帮已知X^2y=3,求2xy乘(x^5y^2-3x^3y-4x)
来源：学生作业帮助网 编辑：作业帮 时间：2024/04/27 17:47:34
由X+Y=3XY可得X+Y-XY=2XY,用X+Y-XY替换分母中的2XY,所以(2X+2Y-XY)/(X+Y+2XY)=(2X+2Y-XY)/(2X+2Y-XY)=1
x-3y=0x=3y原式=(2x+y)(x-y)/(x-y)²=(2x+y)/(x-y)=(6y+y)/(3y-y)=7y/2y=7/2
x-3y=0x=3y代入原式=[(2x+y)/(x-y)²](x-y)=(2x+y)(x-y)=(2×3y+y)/(3y-y)=7y/2y=7/2
-xy（x^2y^5-xy^3-y)=-(xy^2)^3+(xy^2)^2+xy^2=-(-2)^3+4-2=8+4-2=10
因为x-y=4xy所以x-2xy-y=2xy2x+3xy-2y=11xyx-2xy-y分之2x+3xy-2y=5.5
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-3y=0x=3y2x+y/x^2-2xy+y^2×(x-y)=(2x+y)/(x-y)^2*(x-y)=(2x+y)/(x-y)=(6y+y)/(3y-y)=7y/2y=7/2
x+y=3xy,所以2x+2y-xy/x+y+2xy=(2×3xy-xy)/(3xy+2xy)=5/5=1
x-3y=0,x=3yx^2-2xy+y^2/2x+y乘（x-y）=(x-y)^2/(2x+y)乘（x-y）=(x-y)^3/(2x+y)=(3y-y)^3/(6y+y)=8y^2/7
x=3y再答：带入再答：3.5
因为xy/x+y=3,所以xy=3（x+y）（1）将式子（1）代入求值式子：2x-3xy+2y/-x+3xy-y=2x-9x-9y+2y/-x+9x+9y-y=-7x-7y/8x+8y=-7/8
答案是3/2你是不是把分母打错了教你个方法因为上下是齐次的直接令x=3y=2带入就行
3/(x-y)=1/xyx-y=3xyy-z=-3xy原式=[(y-x)-2xy]/[2(x-y)+3xy]=[(-3xy)-2xy]/[2(3xy)+3xy]=-5xy/9xy=-5/9
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
带入x=3y,分母为9y^2-6y^2+y^2=4y^2.分子为7y*2y=14y^2.所以原式=7/2.
xy/x+y=3即：xy=3(x+y)(2x-3xy+2y)/(-x+3xy-y)=[2(x+y)-3xy]/[3xy-(x+y)]=[2(x+y)-9(x+y)]/[9(x+y)-(x+y)]=-7
∵x-y/xy=3∴x-y=3xy2x+3xy-2y/x-2xy-y=[2(x-y)+3xy]/[(x-y)-2xy]=(6xy+3xy)/(3xy-2xy)=9xy/(xy)=9
原式=-xy²（x²y^4-xy²-1）∵xy²=-2原式=2（（-2)²-（-2）-1）=10