f o g) (x) = f [ g(x) ] = f[ 1 /(x-5) ] = 1 /(x-5) / [1 /(x-5) + 4]
= 1 /(x-5) / [1 /(x-5) + 4(x-5) / (x-5)]
= 1 /(x-5) / [(1+4(x-5)] /(x-5)
= [ 1 .(x-5)] / [(x-5)(1+4(x-5)]
= (x-5) / [(x-5) + 4(x-5)²]
= 1 / [1+4(x-5)]
= 1 / [1 + 4x - 20]
= 1 / (4x-19)
2 votes Thanks 3
albitarosita55pc10yf
El dominio de (f o g) (x) es tal que el único valor de x que no está permitido es el que hace que (4x - 19) sea igual a cero. Es decir, el valor de x que hace que 4x - 19 = 0 . x = 19/4
Respuesta: (f o g) (x) = 1 / (4x-19)
Explicación paso a paso:
f o g) (x) = f [ g(x) ] = f[ 1 /(x-5) ] = 1 /(x-5) / [1 /(x-5) + 4]
= 1 /(x-5) / [1 /(x-5) + 4(x-5) / (x-5)]
= 1 /(x-5) / [(1+4(x-5)] /(x-5)
= [ 1 .(x-5)] / [(x-5)(1+4(x-5)]
= (x-5) / [(x-5) + 4(x-5)²]
= 1 / [1+4(x-5)]
= 1 / [1 + 4x - 20]
= 1 / (4x-19)