AMATHS一條f.4

x3y – 2x2y2+ xy3 = 9
Differentiate bothsides with respect to x
[x3 dy/dx+ y d(x3)/dx] – 2[x2 d(y2)/dx + y2d(x2)/dx] + [x d(y3)/dx + y3 dx/dx] = 0
(x3 dy/dx+ 3x2y) – 2(2x2y dy/dx + 2xy2) + (3xy2dy/dx + y3) = 0
(x3 – 4x2y+ 3xy2)dy/dx = -3x2y + 4xy2 – y3
dy/dx = -y(3x2– 4xy + y2) / x(x2 – 4xy + 3y2)
dy/dx = -y(3x - y)(x- y) / x(x - y)(x – 3y)

dy/dx .....
咁都叫F.4
你都好勁WOR
F.5 程度啦