已知y≠0,且3x²-2xy--搜答案-智慧作业帮

3x^2－2xy－8y^2＝0,（3x+4y)(x-2y)=03x+4y=0,或,x-2y=03x=-4y,或,x=2yx/y=-4/3,或,x/y=2

x-3y=0x=3yx*2-xy+y*2/x*2+xy+y*2=(9y^2-3y^2+y^2)/(9y^2+3y^2+y^2)=7y^2/13y^2=7/13

3x²-2xy-8y²=0两边同除y²得:3(x/y)²-2(x/y)-8=0(3x/y+4)(x/y-2)=0x/y=2或x/y=-4/3

因为xy不为0,所以3x^2-2xy-8y^2=0可以两边同时除以y^2,得3(x/y)^2-2(x/y)-8=0即(3x/y+4)(x/y-2)=0解得x/y=2或者x/y=-4/3希望有用.

答：x-7y=0x=7y≠0所以：x/y=7,y/x=1/7(x²-3xy+y²)/(2x²﹢xy-3y²)=(x/y-3+y/x)/(2x/y+1-3y/x)

∵x-y=6,xy=4∴(x-y)²=36∴x²-2xy+y²=36∴x²+y²=36+2×4=44两边除以xyx/y+y/x=44/4=11∴xy^

3x²-2xy-8y²=0(x-2y)(3x+4y)=0x=2y或3x=-4yx/y=2或x/y=-4/3

解题思路：将原方程右边分解因式为（x-4y)(x+y)=0,可得x=4y或x=-y,进而可求出x与y的比值。解题过程：解：∵x2-3xy-4y2=0∴（x-4y)(x+y)=0∴x=4y或x=-y∵x

3x²-2xy-8y²=0(x-2y)(3x+4y)=0x=2y或x=-4y/3x/y+y/x=2+1/2=2.5或x/y+y/x=-4/3-3/4=-25/12

xy≠0,所以x≠0,y≠03x²-2xy-8y²=0两边除于xy3（x/y）-2-8（y/x）=0设x/y=t;t≠03t-8/t-2=03t²-2t-8=0(t-2)

填：3x+2y-2xy=02y+3x=2xy(2y+3x)/(2xy)=1(1/x)+(3/y)=1根据均值不等式得1≥2√(3/(xy))1≥12/(xy)xy≥12所以xy的最小值是12

(x+y)(3x-4y)=0所以y=-x或y=3x/4y=-x原式=(x+2x)/(x-2x)=-3y=3x/4原式=(x-3x/2)/(x+3x/2)=-1/5

2分之1或负4分之3

无解

已知|X|=3,|Y|=2,且XY

B因为XY

已知x>y,且xy

Bxyy那么x为正数,因为负数a为任意有理数a^2等于0所以选B

因为,x-y=3xy所以：-3x+6xy+3y/[(7x-5y)-9xy-(3x-y)]=[-3(x-y)+6xy]/[(7x-5y)-9xy-(3x-y)]=[-3*3xy+6xy]/[7x-5y-

2X^2+3xy-2y^2=0(2x-y)(x+2y)=0即：2x-y=0或,x+2y=0y=2x或x=-2y当y=2x时：x+y/x-y=3x/(-x)=-3当x=-2y时：x+y/x-y=-y/(

∵x-y=4xy∴原式=[2(x-y)+3xy]/[-(x-y)-2xy]=(8xy+3xy)/(-4xy-2xy)=11xy/(-6xy)=-11/6