12x+20y=20x+12y

12x+20y=20x+12y 12x+20y=20x+15y 解方程 {x+y=20 x-y=12 x+y=18 x/12 +y/8 =20 x+y=180 x/12+y/8=20x+y=180x/12+y/8=20 化简求值:(x+y)-(2x+1/2y)-(3x+1/6y)-(4x+1/12y)-(5x+1/20y)-.(10x+1/90y) ,其中x=1,y=-2 (x*x+y*y)(x*x+y*y)-(x*x+y*y)=12 求x*x+y*y等于多少 化简(x+y)-(2x+y/2)-(3x+y/6)-(4x+y/12)-(5x+y/20)-……-(10x+y/90) 解方程组 x+2y=1.5,12(x+y)+15y=20 x.y都是自然数,且x(x-u)-y(y-x)+12,求x.y得值快1且x(x-y)-y(y-x)=12 2X-3Y=12 3X-4Y=17加减消元法3x+2y=94x-2y=52x-3y=123x-4y=175x-5y=715x+20y=72x+3y=56x-5y=-6 x+x+x+y=20 x+x+y=14 x=?y=? [(y*y*y-y)/(xy+1)*(xy+1)-(x+y)*(x+y)]/[(x+y)*y/(x+1)]其中x=-11,y=1/12,化简再求值. 二元一次方程 (1)、20y/x=12 (2)、20(x-y)/x=8 x+y=20,x-y=10,y= (X,Y) f(x,y)={12y^2,0 12y(x-y)^2-8(x-y)^3=? 已知|x|+x+y=10 |y|+x-y=12 求 x+y=?