Derivative of 1/(1-x)

1. Let $u = 1 - x$.

2. Apply the power rule: $\frac{1}{u}$ goes to $- \frac{1}{u^{2}}$

3. Then, apply the chain rule. Multiply by $\frac{d}{d x} \left(1 - x\right)$:

   1. Differentiate $1 - x$ term by term:

      1. The derivative of the constant $1$ is zero.

      2. The derivative of a constant times a function is the constant times the derivative of the function.

         1. Apply the power rule: $x$ goes to $1$

         So, the result is: $-1$

      The result is: $-1$

   The result of the chain rule is:

   $$\frac{1}{\left(1 - x\right)^{2}}$$

4. Now simplify:

   $$\frac{1}{\left(x - 1\right)^{2}}$$

The answer is:

$$\frac{1}{\left(x - 1\right)^{2}}$$