求3x平方-2y平方 3x-3y-2017的值-搜答案-百度作业网

x/y=3x=3y(x^2+y^2-xy)/(x^2-y^2)=(9y^2+y^2-3y^2)/(9y^2-y^2)=7y^2/8y^2=7/8

3x^2+xy-2y^2=(3x-2y)(x+y)=0x=-2y/3,或x=-y但由于你要求的式子中分母里有X平方-Y平方x=-y舍去其他就代入吧

4x^2-3y^2=73x^2+2y^2=19相加7x^2-y^2=26所以14x^2-2y^2=2(7x^2-y^2)=2*26=52

(3x平方-4y平方)+[-(x平方-2xy-y平方)]-[(3x平方-2xy-y平方)]=3x²-4y²-x²+2xy+y²-3x²+2xy+y&#

2(y-x)²-7(x-y)+6(x-y)-3(y-x)²=-(y-x)²-(x-y)=-(x-y)²-(x-y)=-(x-y)[(x-y)+1]=(y-x)(

原方程左边=（2x-y）（x+2y）=0所以x=y/2或x=-y/2将x的值分别代入到x+y/x-y得-3或-1/3

∵x²+y²+2=3∴x²+y²=3-2=1∴-3x²-3y²=-3

{2(x平方y)平方-5x三次方y+3x平方y平方}除以x平方y=（2x的4次方y²-5x³y+3x²y²）÷x²y=2x²y-5x+3y不

当x=-4y=-2时求代数式-3x平方y+3xy平方+x?+3x平方y-3xy平方-y,=-3x²y+3xy²+x-y+3xy(x-y)=-3xy(x-y)+(x-y)+3xy(x

y=2x/3则xy=2x2/3y2=4x2/9所以原式=(2x2/3)/(x2+4x2/9)-(4x2/9)/(x2-4x2/9)=(2/3)/(1+4/9)-(4/9)/(1-4/9)=6/13+4

因为x²+y²-4x+2y+5=0所以(x²-4x+4)+(y²+2y+1)=0所以(x-2)²+(y+1)²=o所以x=2y=-1所以下面

(x-3y)(x+y)-(x-2y)(x+2y)-(x-y)平方=x²-2xy-3y²-x²+4y²-x²+2xy-y²=(x²-

(x+y)(x-y)-y^2+(x-y)^2-(6x^2y-2xy^2)/(2y)=X^2-y^2-y^2+X^2+y^2-2xy-3x^2+xy=-x^2-y^2-xy=-(x^2+y^2+xy-3

x²-x-x²+y=-3-x+y=-3x-y=3x²+y²-2xy=(x-y)²=3²=9

x｛x-1｝-｛x＾2-y｝＝-3即x^2-x-x^2+y=-3-x+y=-3x-y=3而x＾2+y＾2-2xy=(x-y)^2=3^2=9

[(3x-3y)/(y平方-x平方)+(x平方-2xy+y平方)/(x平方-y平方)-(x平方-x+6)/(x+2)]/(x+y)=【-3/(x+y)+(x-y)/(x+y)-(x-3)]】/(x+y

先由两已知方程解得x=27/8,y=9/8,然后接下来的自己算啦...两方程的话,先将第二个两边都乘三,再于第一个相减得出y,再将y带进方程得x

y/x－x/y=3,通分得到（y方-x方)/xy=3,得到y方-x方=3xy,两边同乘以-1,得到x方-y方=xy.(2x方+3xy-2y方)/(x方-2xy-y方)=[2(x方-y方)+3xy]/(

x(x-1)-(x²-y)=-3x²-x-x²+y=-3y-x=-3x-y=3x²+y²-2xy=(x-y)²=3²=9

由x-2y=0得x=2y,x²=4y²,当x,y都不为0时,(2x²-3y²)/(x²+5y²)=(8y²-3y²)/(