1/(6X-4Y)-1/(6X+4Y)+3X/(4Y^2-9X^2)=

{3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 ｛4/(x+y)+6/(x-y)=3 ｛9/(x-y)-1/(x+y)=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 已知4x=9y求(1)x+y/y (2)y-x/2x 化简求值：(7x-2y)(3x-2y-1)-(4x+3y)(9x+6y),其中x=2,y=-1 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 9y=3x-(x-1),4(x+y)-(2x+4)=8y 3分之2(X-Y)-4分之X+Y=-1,6(X+Y)-4(2X-Y)=16 解方程组：2(x-y)/3-x+y/4=-1 ,6(x+y)-4(2x-y)=16 一道二元一次方程组!3(x+y)-4(x-y)=4,(x+y)/2+(x-y)/6=1