9x^2-2y=7 则9x^2-6y-3为什么=18

计算(x-y)^7÷(y-x)^6+9-x-y)^3÷(x+y)^2 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 已知x-2y=3,则(2x+y-6)/(3x-y-9)=? 3(x+y)-2(x-y)=11 4(x+y)+3(x-y)=9 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 (7x-2y)(3x-2y-1)-(4x+3y)(9x+6y)其中x=2y=1 3x+2=y 5x+4=y 7x+6=y 9x+8=y 11x=y 联立方程 有的话 3x+2=y 5x+4=y 7x+6=y 9x+8=y 11x=y 3x+2=y 5X+4=Y 7X+6=Y 9X+8=y 11x=y要如何计算 3x+2=y 5x+4=y 7x+6=y 9x+8=y 11x=y怎么解 y-3x=2,y-5x=4,y-7x=6,y-9x=8,y-11x=0方程组,无 已知x,y为实数,根号3x+4 +y^2-6Y+9=0则x+y=? 化简：x-y/x+3y÷x^-y^2/x^2+6xy+9y^2-(xy/x+y) x^3y^2+6x^2y+9x (x+y)^2+6(x+y)+9 帮忙解一些方程组(1)3x-2y=6 2x+3y=17 (2)5x+6y=15.2 3x-2y=-0.4(3)2(x+y)-3y=7 4(x-9)=3(y-2)(4)3(x+y)-4(x-y)=4 x+y/2+x-y/6=1 已知：2x+y=6,x-3y=1 求7y(x-3y)(x-3y)-2(3y-x)(3y-x)