x+y=18 x/12 +y/8 =20
(x*x+y*y)(x*x+y*y)-(x*x+y*y)=12 求x*x+y*y等于多少
【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2=
解方程 {x+y=20 x-y=12
解方程组{x(x+y+z)=6,y(x+y+z)=12,z(x+y+z)=18
解方程组24/(x+y) +24/(x-y) = 7/3 ,8/(x+y) +18/(x-y) = 4/3
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
已知y=根号(x-8)+根号(8-x)+18,求代数式[(x+y)/(根号x+根号y)]-2xy/(x根号y-y根号x)
Y-X=45 (85%Y-X)×8=(Y-35-X)×12
Y-X=45 (80%Y-X)×8=(Y-35-X)×12
x^+y^-4x+8y+20=0,则x+y的值为多少?