x=1.5y+40 y=1/2x+20如何算啊?
先化简再求值(x-y)(x+y)-(x-2y) 的完全平方+x(3x-5y)-(x-y)(x-2y),其中x=1/2 y
y=ln√(x/1+x^2)如何求导?
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
4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6
(x+y)(x+2y)(x+3y)(x+4y)=-40
(3x-y)^2+(3x+y)(3x-y),x=1,y=-2
{3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1
已知4x=9y求(1)x+y/y (2)y-x/2x
1/(x+y)-1/(x+y)=3/20 2/(x+y)+3/(x-y)=19/20 这是
集合N={(x,y)|(x-1)^2}+(y-1)^20},M={(x,y)|x^2+y^2
y=(x^2+x)/(x+1)