Algebra - Function Notation

Tools: pointer cross off highlighter pencil eraser

DIRECTIONS: Select all that apply.

Which of the following functions is true for the following:

$f(6)=51$

$f(x)=7x+9$

$f(x)=-24+3x^2$

$f(x)=5x+10$

$f(x)=x^2+2x+3$

$f(x)=2x^2-21$