SOLUTION: Hi, For the following problem I got the answer 25x^2+20x+4 but it keeps coming incorrect. Can you help me? Use the function to evaluate the indicated expressions and simplify.

Algebra ->  Functions -> SOLUTION: Hi, For the following problem I got the answer 25x^2+20x+4 but it keeps coming incorrect. Can you help me? Use the function to evaluate the indicated expressions and simplify.       Log On


   

Question 197798: Hi, For the following problem I got the answer 25x^2+20x+4 but it keeps coming incorrect. Can you help me?
Use the function to evaluate the indicated expressions and simplify.
f(x) = -5x + 2
(f(x))^2 = ?
thanks!
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
f%28x%29+=+-5x+%2B+2+ Start with the given function


%28f%28x%29%29%5E2+=+%28-5x+%2B+2%29%5E2+ Square both sides


%28f%28x%29%29%5E2+=+%28-5x+%2B+2%29%28-5x+%2B+2%29+ Expand. Remember something like x%5E2=x%2Ax.


FOIL


%28f%28x%29%29%5E2+=+25x%5E2-10x-10x%2B4+ Multiply


%28f%28x%29%29%5E2+=+25x%5E2-20x%2B4+ Combine like terms.


So you were off by a sign...