Question

f (x)=-3x+7 , f (3) .

Answer 1

f (3) = -3x+7
-3.3+7
-9+7
-2

Answer 2

F(x) = -3x + 7 
F(3)

Substituir x por 3

F(3) = - 3 . 3 + 7
F(3) = - 9 +7
F(3) = -2