Respuesta :

Answer:

Step-by-step explanation:

y = 9 - X   is a linear function; x is to the first power.

y = x2 + 1   does NOT represent a linear function; it's a quadratic function.

o            

y=x² + 5    does NOT represent a linear function; it's a quadratic function.

D)

y = [xl - 9  does NOT represent a linear function; it's an absolute value function.  This function has two halves, each of which is a linear function.

But the best answer here is that y = 9 - X   is a linear function; x is to the first power.