SOLUTION: Given f(x) = 4-x-x2, find f(-3)

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Question 78764: Given f(x) = 4-x-x2, find f(-3)
Found 2 solutions by tutor_paul, Edwin McCravy:
Answer by tutor_paul(519) About Me  (Show Source):
You can put this solution on YOUR website!
I assume that last term is x^2, so I will write the equation as:
f%28x%29=4-x-x%5E2
To find f(-3), just substitute in -3 everywhere there is an x.
f%28-3%29=4-%28-3%29-3%5E2
You should be able to solve it from here.
Good Luck,
tutor_paul@yahoo.com

Answer by Edwin McCravy(20054) About Me  (Show Source):
You can put this solution on YOUR website!

Given f(x) = 4 - x - x², find f(-3)

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

f(x) does NOT mean fx.  It means

"Plug in for x on my right side
whatever is in the parentheses and 
simplify"

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