SOLUTION: i need help with these questions. if f(x)=2x^2=7x+3 find f(2) and f(-3)

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Question 112081: i need help with these questions.
if f(x)=2x^2=7x+3 find f(2) and f(-3)
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

f%28x%29=2x%5E2%2B7x%2B3 Start with the given function.


f%282%29=2%282%29%5E2%2B7%282%29%2B3 Plug in x=2. In other words, replace each x with 2.


f%282%29=2%284%29%2B7%282%29%2B3 Evaluate %282%29%5E2 to get 4.


f%282%29=%2B8%2B7%282%29%2B3 Multiply 2 and 4 to get 8


f%282%29=%2B8%2B14%2B3 Multiply 7 and 2 to get 14


f%282%29=25 Now combine like terms


-----------Now let's evaluate another value---------


f%28x%29=2x%5E2%2B7x%2B3 Start with the given function.


f%28-3%29=2%28-3%29%5E2%2B7%28-3%29%2B3 Plug in x=-3. In other words, replace each x with -3.


f%28-3%29=2%289%29%2B7%28-3%29%2B3 Evaluate %28-3%29%5E2 to get 9.


f%28-3%29=%2B18%2B7%28-3%29%2B3 Multiply 2 and 9 to get 18


f%28-3%29=%2B18%2B-21%2B3 Multiply 7 and -3 to get -21


f%28-3%29=0 Now combine like terms