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Homework Statement
1. If f(x), g(x) and h(x) are real functions of x, show that
when [tex]h(x)=[f(x)]^{g(x)}[/tex]
then [tex]h'(x)=[f(x)]^{g(x)}(g'(x)\ln[f(x)]+g(x)\frac{f'(x)}{f(x)})[/tex]
2. [tex]\frac{A}{x}+\frac{B}{P-x}=\frac{1}{x(P-x)}[/tex] where x is a variable, and P is a constant. Find A and B in terms of P.
Homework Equations
The Attempt at a Solution
1. I start by doing what I usually do, like with [tex]x^{x^2}[/tex]:
[tex][f(x)]^{g(x)-1}.g(x).g'(x)[/tex]
Looking at the derivative, I see
[tex]\int{g'(x)\ln[f(x)]+g(x)\frac{f'(x)}{f(x)}}=g(x)\ln[f(x)][/tex]
Which looks nothing like what I got :(
2. Getting a common denominator and canceling:
[tex]A(P-x)+Bx=1[/tex]
Then by inspection,
[tex]A=\frac{P}{P^2}[/tex]
[tex]B=\frac{1}{P^2}[/tex]
It was a fluke that I got that :/. So I'm wondering how to prove it arithmetically, or just some general method of solving these kinds of problems for when I come across them again.