Hay que separar esa fracción para que se vea más fácil
<img src="https://tex.z-dn.net/?f=%24%5Cfrac%7B1%7D%7Bs%28s%5E2%2B4s%2B6%29%7D%3D%5Cfrac%7BM%7D%7Bs%7D%2B%5Cfrac%7BPs%2BQ%7D%7Bs%5E2%2B4s%2B6%7D%24" />
<img src="https://tex.z-dn.net/?f=%24%5Cfrac%7B1%7D%7B6s%7D-%5Cfrac%7B2%7D%7B3%28s%5E2%2B4s%2B6%29%7D-%5Cfrac%7Bs%7D%7B6%28s%5E2%2B4s%2B6%29%7D%24" />
<img src="https://tex.z-dn.net/?f=%24%5Cfrac%7B1%7D%7B6s%7D-%5Cfrac%7B2%7D%7B3%5Cleft%5B%28s%2B2%29%5E2%2B%5Csqrt%7B2%7D%5E2%5Cright%5D%7D-%5Cfrac%7Bs%7D%7B6%5Cleft%5B%28s%2B2%29%5E2%2B%5Csqrt%7B2%7D%5E2%5Cright%5D%7D%24" />
Apliquemos la TIL
<img src="https://tex.z-dn.net/?f=%24L%5E%7B-1%7D%5Cleft%5C%7B%5Cfrac%7B1%7D%7B6s%7D-%5Cfrac%7B2%7D%7B3%5Cleft%5B%28s%2B2%29%5E2%2B%5Csqrt%7B2%7D%5E2%5Cright%5D%7D-%5Cfrac%7Bs%7D%7B6%5Cleft%5B%28s%2B2%29%5E2%2B%5Csqrt%7B2%7D%5E2%5Cright%5D%7D%5Cright%5C%7D%24" />
Recuerda que la Transformada de Laplace es un operador lineal
<img src="https://tex.z-dn.net/?f=%24L%5E%7B-1%7D%5Cleft%5C%7B%5Cfrac%7B1%7D%7B6s%7D%5Cright%5C%7D-L%5E%7B-1%7D%5Cleft%5C%7B%5Cfrac%7B2%7D%7B3%5Cleft%5B%28s%2B2%29%5E2%2B%5Csqrt%7B2%7D%5E2%5Cright%5D%7D%5Cright%5C%7D-L%5E%7B-1%7D%5Cleft%5C%7B%5Cfrac%7Bs%7D%7B6%5Cleft%5B%28s%2B2%29%5E2%2B%5Csqrt%7B2%7D%5E2%5Cright%5D%7D%5Cright%5C%7D%24" />
Pongámoslo así
<img src="https://tex.z-dn.net/?f=%24L%5E%7B-1%7D%5Cleft%5C%7B%5Cfrac%7B1%7D%7B6s%7D%5Cright%5C%7D-L%5E%7B-1%7D%5Cleft%5C%7B%5Cfrac%7B1%7D%7B3%5Cleft%5B%28s%2B2%29%5E2%2B%5Csqrt%7B2%7D%5E2%5Cright%5D%7D%5Cright%5C%7D-L%5E%7B-1%7D%5Cleft%5C%7B%5Cfrac%7Bs%2B2%7D%7B6%5Cleft%5B%28s%2B2%29%5E2%2B%5Csqrt%7B2%7D%5E2%5Cright%5D%7D%5Cright%5C%7D%24" />
<img src="https://tex.z-dn.net/?f=%24%5Cfrac%7B1%7D%7B6%7D%20-%5Cfrac%7B1%7D%7B3%7De%5E%7B2t%7DL%5E%7B-1%7D%5C%7B%5Cfrac%7B1%7D%7Bs%5E2%2B%5Csqrt%7B2%7D%5E2%7D%5C%7D-%5Cfrac%7B1%7D%7B6%7De%5E%7B2t%7DL%5E%7B-1%7D%5C%7B%5Cfrac%7Bs%7D%7Bs%5E2%2B%5Csqrt%7B2%7D%5E2%7D%5C%7D%24" />
<img src="https://tex.z-dn.net/?f=%24%5Cfrac%7B1%7D%7B6%7D%20-%5Cfrac%7B1%7D%7B3%7De%5E%7B2t%7D%5Ccdot%5Cfrac%7B1%7D%7B%5Csqrt%202%7D%5Csin%28%5Csqrt%202%5C%2C%20t%29%20-%5Cfrac%7B1%7D%7B6%7De%5E%7B2t%7D%5Ccdot%20%5Ccos%20%28%5Csqrt2%20%5C%2C%20t%29%24" />
Ahora la ecuación
y'' + 4y' + 6y = 1 + e ^ { - t}, con las condiciones iniciales y(0) = 0, y'(0) = 0
Igualmente la Transformada de Laplace es un operador lineal
<img src="https://tex.z-dn.net/?f=L%5C%7By%27%27%2B4y%27%2B6y%5C%7D%3DL%5C%7B1%2Be%5E%7B-t%7D%5C%7D%5C%5C%0As%5E2L%5C%7By%5C%7D%20-sy%280%29-y%27%280%29%2B4sL%5C%7By%5C%7D-4y%280%29%2B6L%5C%7By%5C%7D%3D1%2Fs%20%2B%201%2F%28s%5E2%2B1%29%5C%5C%0A%28s%5E2%2B4s%2B6%29L%5C%7By%5C%7D%3D1%2Fs%20%2B%201%2F%28s%5E2%2B1%29%5C%5C%0A" />
<img src="https://tex.z-dn.net/?f=%24L%5C%7By%5C%7D%20%3D%5Cfrac%7B1%7D%7B3%7D%5Cleft%5C%7B%5Cfrac%7B1%7D%7Bs%7D-%5Cfrac%7B1%7D%7Bs%2B1%7D-%5Cfrac%7B1%7D%7Bs%5E2%2B4s%2B6%7D%5Cright%5C%7D%24" />
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