Question 78764
<pre><font size = 6><b>
Given f(x) = 4 - x - x², find f(-3)

That's just a easy "plug-in".

f(x) does NOT mean fx.  It means
<i>
"Plug in for x on my right side
whatever is in the parentheses and 
simplify"</i>

When you are given an equation for
f(x) and then asked to find 
f(some number) all you do is plug in
that number for x all the way across.
Then simplify the right side.

Here you are given

     f(x) = 4 - x - x²

and then asked to find f(-3), so all 
you do is take

     f(x) = 4 - x - x²

and every where you see an x put (-3) 
in place of it, like this

     f(x) = 4 - x - x²

    f(-3) = 4 - (-3) - (-3)²

Then you simplify the right side

    f(-3) = 4 + 3 + 9

    f(-3) = 16

and you leave it just like that.
   
Wasn't that easy?  This is probably
one of the easiest things you'll
ever study in algebra.

Edwin</pre>