Respuesta :

(f+g)(x) = f(x) + g(x)
(f+g)(x) = [ f(x) ] + [ g(x) ]
(f+g)(x) = [ 3^x + 10x ] + [ 5x - 3 ]
(f+g)(x) = (3^x) + (10x+5x) + (-3)
(f+g)(x) = 3^x + 15x - 3

So the answer is choice D