4x+8(x+y)=840 4y+9(x+y)=840

4x+8(x+y)=840 4y+9(x+y)=840 9y=3x-(x-1),4(x+y)-(2x+4)=8y 81/8*(-x-y)^6*(x-y)^3*4/9(x+y)^4*(y-x)^2 4(x-y)-3(x-y)=9 5(x-y)+2(x-y)=11 3(x+y)-2(x-y)=11 4(x+y)+3(x-y)=9 X+Y=9 8X+4Y=56 [(x+2y)(x-2y)-(x-2y)^2+8y(x+y)]除以4x= 解方程组{4x+8(x+y)=480,4y+9(x+y)=480 求x ,y 9x^2+4y^2-12x-8y+8=0 计算：(x-y)^8÷(y-x)^4×(x-y) x+x+x+y=60 .x-y=4 (x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= 4+12(x-y)+9(x-y)^ 7x:4y,x:y=( ):( (x-4y)(2x+y)= 5x-4y(y-x)=? 4x+8(x+y)=840 4y+9(x+y)=840二元一次方程组要过程 [(2x-y)^2-y(y-4x)-8x]其中x=-1/2