3xy2dy
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΢·Ö·ûºÅ,dx,dyµ½µ×ÊÇʲôº¬Òå?
Àý3£¬z=x^2-3xy^2\begin{split} dz &=\{(x+dx)^2-3(x+dx)(y+dy)^2\}-\{x^2-3xy^2\}\\ &=\{[x^2+2xdx+dx^2]-...
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(x^3+y^3)dx - 3xy^2dy=0ÇóÆë´Î·½³ÌµÄͨ½â
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(x+y)dx - 3xydy=0µÄͨ½â?
½â´ð x3dx=3xy2dy-y3dx x3dx=xdy3-y3dx xdx=dy3/x+y3d(1/x)ͨ½âx2/2=y3/x+C
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(1)y = 3x^2 - ln 1/x = 3x^2 + lnxdy = 6xdx + (1/x)dx=(6x + 1/x)dx(2)y = e^(-x)cosxdy = -e^(-x)cosxdx - e^(-x)sinxdx= -e^...