q***e
发帖数: 90 | 1 In your particular case, integration factor may be
even simpler.
Multiply both sides of the equation by y, we have
yy''' - 4xy'y - 2yy = 0 (1)
If you obsrve the left side carefully, you can find that it
is a (full) derivative, by integrating both sides, you got
a primary integral of the equation, thus reduce the equation
to second order. If you don't know the jargons above, just
skip and read on.
We can rewrite equation (1) as
(yy'' - 0.5y'y' - 2x |
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