(9x+4y)(9x-4y)=

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 4+12(x-y)+9(x-y)^ 9y=3x-(x-1),4(x+y)-(2x+4)=8y x>0 y>0 x+y=1,4/X+9/y最小值x>0 y>0 x+y=1,求4/X+9/y最小值 已知X.x+y.y-4x+2y+5=0,求4X.X-12X Y+9Y.y的值 根据3（x+y)-2(x-y)=11,4(x+y)+3(x-y)=9可得出x+y= ,x-y= 9x+4y (9x+4y)(9x-4y)= 81/8*(-x-y)^6*(x-y)^3*4/9(x+y)^4*(y-x)^2 x+4y=9,x-4y=10 4(x+y)²-12(x+y)(x-y)+9(x-y)² X+Y=9 8X+4Y=56 4-12(x-y)+9(x-y)²=? 4x+y-9>=0 ,x-y-1 9(x-y)^2-12(x-y)+4=快 4-12(x-y)+9(x-y)的平方= 9(x+y)²-4(x-y)²=?