2y+y=105 2y+4y=15 9x-4x=6.5 8n-n=14 求详解,最好带文字说明的,谢谢了!急！！

x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 2（x+y)-3(x-y)=3 ,4(x+y)+3(x-y)=15 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 y+y'-2y=2x 微分方程y - 2y' + y = x 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) (x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= (x-4y)(2x+y)= y+x=15 2y+4y=44 x= y= y'=（y/x）^2+y/x+4微分方程 2x-y=2,求[(x²+y²)-(x-y)²+2y(x-y)]÷4y 根据3（x+y)-2(x-y)=11,4(x+y)+3(x-y)=9可得出x+y= ,x-y= 已知X.x+y.y-4x+2y+5=0,求4X.X-12X Y+9Y.y的值 4x方y/(x-2y)(x+2y)怎么算[x方/x-2y]-4x方y/(x-2y)(x+2y)=? x^2+y^2=15,x+y=7,x＞y,求x-y (x+y)^2(x-y)^2(x^4+x^2y^2+y^4)=? 3(x+y)+2(x-y)=36 4(x+y)-5(x-y)=2