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- Homework Statement
- $$\frac{h}{h+x-y}\approx 1-\frac x h+\frac y h$$

- Relevant Equations
- .

My physics textbook does the approximation in the homework statement. Here, x and y are variables and are much smaller than h. I attempted to figure out why it is valid with ##(1+x)^-1\sim 1-x##. However, after trying to convert the initial equation into 1+x form, I obtained ##h(1-(h+x-y-1))## which does not equal to ##1-\frac x h+\frac y h##, the desired result. Could anyone tell me why?

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