y=[4/(x^2)] +{9/[400-(x^2)]}
已知4x=9y求(1)x+y/y (2)y-x/2x
9y=3x-(x-1),4(x+y)-(2x+4)=8y
已知X.x+y.y-4x+2y+5=0,求4X.X-12X Y+9Y.y的值
y=(x-1)(x-2)(x-3)(x-4)(x-5)(x-6)(x-7)(x-8)(x-9)(x-10)的导数在x=1
y=[4/(x^2)] +{9/[400-(x^2)]}
{3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1
x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20
{(x+y)/2+(x-y)/3=6 4(x+y)-3(x-y)=-20
3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27
4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6
(x+y)(x+2y)(x+3y)(x+4y)=-40
已知x/y=3/2求代数式4x-9y/2x+3y