SOLUTION: find f(-3) when f(x)=2x^2-7x+8.

Algebra ->  Functions -> SOLUTION: find f(-3) when f(x)=2x^2-7x+8.       Log On


   

Question 115662: find f(-3) when f(x)=2x^2-7x+8.
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

Let's evaluate f%28-3%29


f%28x%29=2x%5E2-7x%2B8 Start with the given function.


f%28-3%29=2%28-3%29%5E2-7%28-3%29%2B8 Plug in x=-3. In other words, replace each x with -3.


f%28-3%29=2%289%29-7%28-3%29%2B8 Evaluate %28-3%29%5E2 to get 9.


f%28-3%29=%2B18-7%28-3%29%2B8 Multiply 2 and 9 to get 18


f%28-3%29=%2B18%2B21%2B8 Multiply -7 and -3 to get 21


f%28-3%29=47 Now combine like terms