Las expresiones son :
<img src="https://tex.z-dn.net/?f=%28x%2B1%29" />
<img src="https://tex.z-dn.net/?f=%28x-1%29" />
Pero sabemos que :
1.
- <img src="https://tex.z-dn.net/?f=%28x%2B1%29%28x-1%29%3Dx%5E%7B2%7D-1" />
Luego si a (1) le sumamos 2 y 4 se obtiene :
2.
- <img src="https://tex.z-dn.net/?f=x%5E%7B2%7D-1%2B2%3Dx%5E%7B2%7D%2B1" />
3.
- <img src="https://tex.z-dn.net/?f=x%5E%7B2%7D-1%2B4%3Dx%5E%7B2%7D%2B3" />
Así dividiendo (2) y (3) entre los factores de (1) se tiene :
<img src="https://tex.z-dn.net/?f=%5Cfrac%7Bx%5E%7B2%7D%2B1%7D%7Bx%2B1%7D%3D%28x-1%29%5Cfrac%7B2%7D%7Bx%2B1%7D" />
<img src="https://tex.z-dn.net/?f=%5Cfrac%7Bx%5E%7B2%7D%2B3%7D%7Bx-1%7D%3D%28x%2B1%29%5Cfrac%7B4%7D%7Bx%2B1%7D" />
Si a (1) le sumamos <img src="https://tex.z-dn.net/?f=%20x%5E%7B2%7D-1" /> se obtiene :
4.
- <img src="https://tex.z-dn.net/?f=x%5E%7B2%7D-1%2B%28x%5E2-1%29%3Dx%5E2-1%2Bx%5E%7B2%7D-1%3D%202x%5E%7B2%7D-2" />
Finalmente dividiendo (4) entre (1) obtenemos :
<img src="https://tex.z-dn.net/?f=%5Cfrac%7B2x%5E%7B2%7D-2%7D%7Bx%5E%7B2%7D-1%7D%3D2" />
Saludos.