SOLUTION: Given f(x) = 5x^ - 3x + 1, how would I find f(-2)?

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Question 120523: Given f(x) = 5x^ - 3x + 1, how would I find f(-2)?
Found 2 solutions by jim_thompson5910, tutor_paul:
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!


f%28x%29=5x%5E2-3x%2B1 Start with the given function.


f%28-2%29=5%28-2%29%5E2-3%28-2%29%2B1 Plug in x=-2. In other words, replace each x with -2.


f%28-2%29=5%284%29-3%28-2%29%2B1 Evaluate %28-2%29%5E2 to get 4.


f%28-2%29=%2B20-3%28-2%29%2B1 Multiply 5 and 4 to get 20


f%28-2%29=%2B20%2B6%2B1 Multiply -3 and -2 to get 6


f%28-2%29=27 Now combine like terms

Answer by tutor_paul(519) About Me  (Show Source):
You can put this solution on YOUR website!
I assume you meant 5x^2, but if not, repost it...
f%28x%29=5x%5E2-3x%2B1
To find f(-2), just plug in -2 everywhere you see x and simplify:
f%28-2%29=5%2A%28-2%5E2%29-3%2A%28-2%29%2B1
f%28-2%29=5%2A4-3%2A%28-2%29%2B1
f%28-2%29=20%2B6%2B1
highlight%28f%28-2%29=27%29
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Good Luck,
tutor_paul@yahoo.com