化简:6(0.9y-x)=9(y-30-x)

化简:6(0.9y-x)=9(y-30-x) 化简 x / y(x+y) - y / x(x+y) = {6/x+y+10/x-y=30 6/x+y-10/x-y=-1 化简：x-y/x+3y÷x^-y^2/x^2+6xy+9y^2-(xy/x+y) x@y=(x+y)除以2,X#Y=3X-Y除以2 问：(9@x）#30=6,求x的值. 常微分方程的通解dy/dx=(x-y+1)/(x+y-3)y^4=2y^n+y=0y''+6y'+9y=e^(-3x)y''+y'-2y=4e^(2x) 、1.2x+9y=81 3x+y=341.2x+9y=81 3x+y=34 2.9x+4y=35 8x+3y=30 3.7x+2y=52 7x+4y=62 4.4x+6y=54 9x+2y=87 5.2x+y=7 2x+5y=19 6.x+2y=21 3x+5y=56 7.5x+7y=52 5x+2y=22 8.5x+5y=65 7x+7y=203 9.8x+4y=56 x+4y=21 10.5x+7y=41 5x+8y=44 11.7x+5y=54 3x+4y=38 12.x+8y=15 (x-y)³+9(x-y)-6(x-y)² 化简:x-y/x+3y÷x^2-y^2/x^2+6xy+9y^2-2y/x+y 化简:x-y/x+3y÷x^2-y^2/x^2+6xy+9y^2-2y/x+y 化简x+3y分之x-y÷x²y²分之x²+6xy+9y²-x+y分之2y 化简：(1)(x+1)^2-x(x^2+x-1)-(x^2+1)^0(2)(y-2)(y^2-6y-9)-y(y^2-2y-15) 化简 x-y/(y-x)^3= X+Y=9 6X+7Y=59 x+2y=6 2x+y=9 2x+6y-x²+9y²=? (x+y)²+6(x+y)+9 (x+y)^2+6(x+y)+9