SOLUTION: if f(x)=x^2+3x+4 find f(-1)

Algebra ->  Graphs -> SOLUTION: if f(x)=x^2+3x+4 find f(-1)      Log On


   

Question 281375: if f(x)=x^2+3x+4 find f(-1)
Answer by Mathematicians(84) About Me  (Show Source):
You can put this solution on YOUR website!
The notation of f(-1) is a tricky one. Basically, you take the -1 and plug it in for all the x's.
For your example:
f%28x%29=x%5E2%2B3x%2B4+
is really
f%28-1%29+=+%28-1%29%5E2+%2B+3%28-1%29+%2B+4
When you square a negative, it is the same thing as multiplying a negative with a negative which turns into positive so:
%28-1%29%5E2+%2B+3%28-1%29+%2B+4+=+1+-3+%2B+4+=+2
Basically f%28-1%29+=+2