Respuesta :

9514 1404 393

Answer:

  x^2 +4x -21

Step-by-step explanation:

Substitute the given expressions and simplify.

  f(x) + g(x)

  = (x^2 +3x -28) +(x +7)

  = x^2 +(3+1)x +(-28 +7)

  = x^2 +4x -21