1/4x^4-( )+4/9y^2=( )^2

9y=3x-(x-1),4(x+y)-(2x+4)=8y {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 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)/4+(x+y)/5=1/4 (x+y)/9-(x-y)/3=//2(x-y)/4+(x+y)/5=1/4(x+y)/9-(x-y)/3=//2 解二元一次方程 {3(x+y)-4(x-y)=-9 x+y/2+x-y/6=1 已知4x=9y求(1)x+y/y (2)y-x/2x有关比例的 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+2(-x-y+1)=3(1-y-x)-4-(y+x-1),x+y=? 已知:【(x²+y²)-(x-y)²+2y(x-y)】/4y=1,求4x/4x²-y²-1/2x+y 先化简 再求值 (2x-y)(y+x)-(x-2y)(2y+x)-(-3y+x)^2其(√x+1)+y^2+4=-4y 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 已知x-y=1,求[(x+2y)^2+(2x+y)(x-4y)-3(x+y)(x-y)]除以y的值大神们帮帮忙 已知x-y=1,求[(x+2y)²+(2x+y)(x-4y)-3(x+y)(x-y)]÷y的值 化简(x+y)+(2x+1/2y)+(3x+2/3y)+(4x+3/4y)+...+(9x+8/9y)=? (7x-2y)(3x-2y-1)-(4x+3y)(9x+6y)其中x=2y=1 [(y-2x)(-2x-y)-4(x-2y)²]*2y,其中x=1,y=2 {5(x-3y)-6=2x+1 3(x+6y)+4=9y+19 ｛3分之2（x-y）=4分之x+y-1 6）x+y)=4(2x-y)+16