Urgent question

1)



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2)

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2. y = xe^y

lny = ln(xe^y) = lnx + lne^y = lnx + y

Differentiate both sides w.r.t. x

1/y dy/dx = 1/x + dy/dx

(1/y - 1)dy/dx = 1/x

dy/dx = y/[x(1 - y)]

2010-05-01 13:16:17 補充：
Differentiate both sides w.r.t. x

d^2y/dx^2 = {x(1 - y)dy/dx - y[x(-dy/dx) + (1 - y)]}/[x(1 - y)]^2

= [y + y^2/(1 - y) - y + y^2] / [x(1 - y)]^2

= (2y^2 - y^3)/[x^2(1 - y)^3]