therefore
1/y * y' = v (x)' lnu (x)+v (x) * u' (x)/u (x) is the derivative of the equation lny=V(x)lnu(x) with respect to x.
Implicit function: in an equation f(x, y)? =? 0, if x takes any value in a certain interval, there is always a corresponding y that satisfies this equation, then it can be said that the equation f(x, y)? =? 0 determines the implicit function y of x in this interval, such as x2? +? y2? 1? =? 0。 Functions that can be directly expressed by expressions with independent arguments are called explicit functions, which are generally called functions, such as y? =? cos(x).
The simple understanding is that
For example, function F(x, y), if y is a function about x, then function F(x, y) is an implicit function.
This problem is actually to find the implicit function. You can substitute y into the above steps.