500X=1200+4y 20Y=2400+20X 解得X=3.39 Y=123.39

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 解方程 {x+y=20 x-y=12 有这样一道题,计算：（x-y)[(x+y)(x+y)-xy]-(x-y)[(x-y)(x-y)+xy]的值,其中x=20 解方程组4x+y=53x-2y=1得x=1y=1，把 十万分,[3x+2y]/2=[2x+y]/3=[x-y+1]/4 解得. 4X+2Y=58 X+Y=20 X=?Y=? 已知x+y=4,x²-y²=20,则x-y=? x平方-y平方=20,x+y=4求x-y=? 解方程组x+y+√(x+y)=20;x²+y²=136 已知x-y=4,x²-y²=20,求x-y的值