3X+10Y=14 10X+15Y=32

10/(x+y)+3/(x-y)=-5.(1)15/(x+y)-2/(x-y)=-1.(2)(1)×3-(2)×2得：(9+4)/(x-y)=-13x-y=-1.(4)(1)×2+(2)×3得：(20

(4x-2y-z)-{5x[8y-2y-(x+y)]-x+(3y-10z)]=4x-2y-z-5x[6y-(x+y)]+x-(3y-10z)=4x-2y-z-30xy+5x²+5xy+x-3

(x+y)/6+(x-y)/10=3①(x+y)/6+(y-x)/10=-1②①可变为：(x+y)/6-（y-x)/10=3③②+③=(x+y)/3=2得x+y=6④②-③=（y-x）/5=-4得y-

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+3y=103x+2y=15,把两式相加得：5x+5y=25,x+y=5,把两式相减得：-x+y=-5,x-y=5,(x+y)(x-y)=5×5=25

-3(2x-y)-{7x-[6x+2y-(10x-8y)]-x-2(3x-4y)}=-6x+3y-7x+(6x+2y-10x+8y)+x+6x-8y=-13x+3y-4x+10y+7x-8y=-10x

﹛（x+y）分之10+（x-y）分之3=-5﹛（x+y)分之15-（x-y)分之2=-1设（x+y)=ax-y=b则：10/a+3/b=-5①15/a-2/b=-1②①×2+②×3得：20/a+45/

1、2X-3Y＝101）-4X+Y＝52）1）×2+2）得4X-6Y-4X+Y＝20+5-5Y＝25Y＝-5把Y＝-5代入2）中,得-4X-5＝5X＝-5/2解得X＝-5/2,Y＝-52、3X-2Y＝

X+Y分之X-Y等于3x=-2yX+Y分之2(x-y)减X+Y分之3X+Y=(-x-3y)/(x+y)=1

.死算呗xy-2x+3y-6=xy+10x-3y-30,2x-y=4xy+3x+y+3=xy+12x-2y-24,3x-y=92式减1式,x=5,y=6

因为(x-y)/(x+y)=3,则(x＋y)/(x－y)＝1/3则5(x-y)(x+y)-(x+y)/2(x-y)＝5*3-1/(3*2)=15-1/6=89/6

化简x+y=105x+7y=625x+5y+2y=622y=62-50y=6x=4

①－②可得：x-y/10－y-x/10=4x-y／5＝4x-y＝20——③①＋②可得：x+y/3=2x+y=6——④由③④可得：x=13,y=－7

5(x+y)-2x=03x+5y=06x+10y=0①3x-10(x+y)=27x+10y=-2②②-①x=-2代入①y=6/5

方程组整理得：2(x+y)-3(x-y)=3①4(x+y)+3(x-y)=15②①+②得x+y=3③，把③代入①，得x-y=1④，③+④得：x=2，③-④得：y=1，则原方程组的解是x=2y=1．

x2-3x=1x2-6x=-5x2-6x9=-59（x-3）=4x-3=±2x1=1x2=5y23y-2=0y23y2.25=22.25（y1.5）=4.再问：我不明白呀3X+7Y=152X-5Y=-

-3(2x-y)-{7x-〔6x+2y-（10x-8y）〕-x-2(3x-4y)}=-6x+3y-{7x-6x-2y+10x-8y-x-6x+8y}=-6x+3y-(4x-2y)=-10x+5y由(x

这慢慢做不就好了,这么简单的式子

什么意思?再问：tangram_guid_1358503626031再答：1：2x+3y=7,3x-5y=1;x=2y=12:3x+5y=5,3x-4y=23;x=5y=-23:3x+5y=5,3x-