{9y=3x-(x-1),4(x y)-(2x 4)=8y解方程组

[(2x+y)^2+(y+2x)(y-2x)-2y(4x-y)]/4y=(4x^2+4xy+y^2+y^2-4x^2-8xy+2y^2)/4y=(-4xy+4y^2)/4y=-x+y=-1/2+1/3

原式=(9x²+24xy+16y²-4x²+y²-5x²+6xy-y²)÷(-2y)=(30xy+16y²)÷(-2y)=-15x

(1)=(x-y)(x+1)(x-1)(2)=x(x^2+x+1/4x)=x(x+1/2)^2(3)=4x^2+4xy+y^2-x^2+4xy-4y^2=3x^2+8xy-3y^2=(3x-y)(x+

3(x+y)+3(y-x)=1(1)3(x+y)+4(y-x)=-1(2)(2)-(1)得y-x=-2(3)代入（1）3（x+y)-6=1x+y=7/3=>x=7/3－y又由（3）得x=y+2y+2=

设a=(x-1)(x-2)(x-3)(x-4)(x-5)(x-6)(x-7)(x-8)(x-9)那么y=a*(x-10);那么y^=a^*(x-10)+a*(x-10)^=a^*(x-10)+a那么y

(2x-y)(2x+y)+(2x-y)(y-4x)+2y(y-3x)=4x^2-y^2+2xy-8x^2-y^2+4xy+2y^2-6xy=-4x^2=-4(-1/4)^2=-1/4

这是三个题吗?1.x=10/3y=22.x=2/3y=33.x=-109/400y=-3/100

(6X+4Y)/(36X2-16Y2)-(6X-4Y)/(36X2-16Y2)=2Y/(9X2-4Y2)再+3X/(4Y^2-9X^2)=(2Y-3X)/(4Y^2-9X^2)=2Y+3X

化简（x+y）+(2x+y/1*2)+(3x+y/2*3)+...+(9x+y/8*9),并求当x=2,y=9时的值（x+y）+(2x+y/1*2)+(3x+y/2*3)+...+(9x+y/8*9)

9y＝2x+1得27y=6x+34y＝3x-4得8y=6x-8上式-下式19y＝11y＝11/19x＝40/19

(7x-2y)(3x-2y-1)-(4x+3y)(9x+6y)=21x^2-14xy-7x-6xy+4y^2+2y-36x^2-24xy-27xy-18y^2=-15x^2-70xy-7x-14y^2

你这根号是在是描述的不清楚,不过已知式子可以化为：(x-2)^2+(y-3)^2=0从而得出x=2y=3,这个知道了后面你那个长长的式子直接代入值就可以解出来了因为我看不明白你这些根号所以最后答案没给

3(x+y)-4(x-y)=4(x+y)/2+(x-y)/6=1令a=x+y,b=x-y3a-4b=4(1)a/2+b/6=1则3a+b=6(2)(2)-(1)5b=2b=2/5a=(6-b)/3=2

4x=9yx=9/4*y(1)(x+y)/y=[(9/4)y+y]/y=(9/4+1)y/y=9/4+1=13/4(2)(y-x)/2x=[y-(9/4)y]/[2*(9/4)y]=(1-9/4)y/

令a=1/(x+y),b=1/(x-y)4a+6b=3(1)9b-a=1(2)(1)+(2)×46b+36b=3+442b=7b=1/6a=9b-1=1/2所以x+y=1/a=2x-y=1/b=6相加

{4/x+y+6/x-y=3{9/x-y-1/x+y=1令1/(x+y)=a,1/(x-y)=b则原方程组为{4a+6b=3{-a+9b=1解得{a=1/2{:b=1/6所以{x+y=2{x-y=6解

x（x*x-1)+x(5-x*x)-6y+7=-x+5x-6y+7=2(2x-3y)+7=2*(-4)+7=-8+7=-1再问：能在写详一点吗-x+5x-6y+7再答：x（x*x-1)+x(5-x*x

解9y=3x-(x-1)2x-9y+1=0①4(x+y)-(2x+4)=8y2x-4y-4=0②②-①得：5y-5=0∴y=1将y=1代入①得：2x-9+1=0∴x=4∴方程的解为：x=4,y=1

完整设1/(x+y)=a,1/(x-y)=b原方程组可变为4a+6b=39b-a=1a=9b-136b-4+6b=3b=1/6,a=1/2x+y=2x-y=6所以原方程组的解为：x=4,y=-2

原式=x-x+x-x+……-x+(2-1+4-3+5-4+……+2008-2007-2009）y=0+(1×1004-2009)y=-1005y=1005/2