圆C:x^2+y^2-4x-6y-12=0 圆中长为8的弦的中点轨迹方程为-----?麻烦 把过程和思路 说下

如果A={（x,y）|x,y+2>0},B={（x,y）|2x+3y-6>0},C={（x,y）|x-4 （x+y）/2- x-y/2=6 3(x+y)=4(x-y) x+y/3+x-y/2=6 4(x+y)-2(x-y)=40 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20 {(x+y)/2+(x-y)/3=6 4(x+y)-3(x-y)=-20 4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6 x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 直线l：x+y-5=0和圆C：x^2+y^2-4x+6y-12=0的位置关系 设A={(x,y)}|3x+2y|.设A={(x,y)}|3x+2y|.B={(x,y)|x-y=2|},C={(x,y)|2x-2y|=3},D={(x,y)|6x+4y=2|},求A∩B,B∩C,A∩D设A={(x,y)|3x+2y=1}.B={(x,y)|x-y=2},C={(x,y)|2x-2y=3},D={(x,y)|6x+4y=2},求A∩B，B∩C，A∩D 解方程组：x+y/2+x-y/3=6 4(x+y)-5(x-y)=12 解方程组{2(x-y)/3 - x+y/4=-1 6(x+y)-41(x-y)=12 8（x-y)=3（x+y)-12 6（x+y)=4（2x-y)+16 8（x-y)=3（x+y)-12 6（x+y)=4（2x-y)+16 几道 数学题急啊 对了再加20分(x+y)^2-(x+y)^3(x-y)^2-(x-y)^3 (x-y)^2-(y-x)^32(x-y)-3(y-x)^24ab(a+b)^2-6a^2b(a+b)(x+y)(x-y)-(x+y)^28a(x-y)^2-4b(y-x)a=-5 a+b+c=-5.2求代数式a^2(-b-c)-3.2a(c+b)的值 谁能帮我因式分解啊.A.4（x-y+1)+y(y-2x) B.5+7x-6x² C.12x²+xy-6y² x^2+y^2+4x-6y+12=0.求x^y的值 3/X+2/Y=6/1等介于?（X不等于18）A.x/3+y/2=1/6 B .3Y+2X C.X=18Y/Y-12 D .Y=12X/X-18