Respuesta :

Answer:

h/12(12+h)

Step-by-step explanation:

if x=7,  f(x)=1/(7+5)=1/12

if x=7+h, f(x)=1/(7+h+5)=1/(12+h)

1/12-1/(12+h)=12+h-12/12(12+h)=h/12(12+h)