Respuesta :
Answer:
x = 30
Step-by-step explanation:
D( x )
x = 0
x = 0
x = 0
x in (-oo:0) U (0:+oo)
4/12 = 10/x // - 10/x
4/12-(10/x) = 0
4/12-10*x^-1 = 0
-10*x^-1 = -1/3 // : -10
x^-1 = 1/30
-1 < 0
1/(x^1) = 1/30 // * x^1
1 = 1/30*x^1 // : 1/30
30 = x^1
x = 30
x = 30