Ihave no clue how to do this. i just need to pass my online math class.

If F(3) then 3=x. So all you would do is substitute 3 in for x

So, if you're trying to find the value of f(3), you substitute x=3 into the equation. However, you must be careful.

Which equation in the function do you substitute it into?

2x-9 or 4-x?

You would substitute x=3 into 2x-9.

Why?

See the inequalities at the end of each equation? Those tell you which values you substitute into the equation. Since x=3, you find which inequality it fits under.

It's not x>3 because 3 is not greater than 3. It would be x≤3 because 3 is a value less than or EQUAL to 3.

Now substitute the value x=3 into the correct equation.

2x-9
2(3)-9
6-9
-3

Therefore f(3) = -3.