1 | initial version |
You don't consider the right equation to solve:
y=function('y')(x)
dy = diff(y)
derivative = solve(diff(y==exp(x*y)), dy)
derivative[0].subs(exp(x*y)==y)
This yields
diff(y(x), x) == -y(x)^2/(x*y(x) - 1)
that is, $$y'=\frac{y^2}{1-xy},$$ in agreement with your hand calculation.