4x^2-1/9y^2

4(x-y+1)+y(y-2x)4x^4-13x²+9 9y=3x-(x-1),4(x+y)-(2x+4)=8y x²/xy-x/y 3x/4x+y - x-2y/4x+y (1-y/y+x)÷x/y²-x² (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 已知4x=9y求(1)x+y/y (2)y-x/2x有关比例的 解二元一次方程 {3(x+y)-4(x-y)=-9 x+y/2+x-y/6=1 因式分解 （1）.(x+y)(x+y-6)+9 （2）.x²-16y²-x-4y 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) 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 3(x+y)-2(x-y)=11 4(x+y)+3(x-y)=9 把4（x-y+1)+y(y-2x)因式分解 y(y+2)+4x(x-y-1)因式分解是多少 化简 x-[y-2x-(x-y) -9-4[2x-5(x+1)] 2x-3{y-[3x-(2y-x)]-2x}过程一步一步的列好x-[y-2x-(x-y) -9-4[2x-5(x+1)] 2x-3{y-[3x-(2y-x)]-2x} {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 把(x+y),(x-y)个作为一个整体合并同类项1,7(x+y)-2(x+y)-4(x+y)+2(x+y)2,(x-y)²＋2(x-y)－(x-y)－2(x-y)² 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